diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 46090ea..830067f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -17,10 +17,10 @@ jobs:
       - name: Install PHP
         uses: shivammathur/setup-php@1a18b2267f80291a81ca1d33e7c851fe09e7dfc4 # v2.22.0
         with:
-          php-version: 7.4
-
-      - name: Install PHPUnit
-        run: wget https://phar.phpunit.de/phpunit-9.5.phar
+          php-version: 8.1
+        
+      - name: Composer install
+        run: composer install --prefer-dist --no-progress --no-suggest --ansi --no-interaction --no-scripts --no-plugins --optimize-autoloader
 
       - name: PHPUnit
-        run: php phpunit-9.5.phar --verbose --colors=always
+        run: vendor/bin/phpunit --verbose --colors=always
diff --git a/README.md b/README.md
index df29409..b47ed95 100644
--- a/README.md
+++ b/README.md
@@ -47,6 +47,7 @@ MS_GITHUB_TOKEN=abc123 php run.php update --cms-major=5 --branch=next-minor --dr
 | --dry-run | Do not push to github or create pull-requests |
 | --account | GitHub account to use for creating pull-requests (default: creative-commoners) |
 | --no-delete | Do not delete _data and _modules directories before running |
+| --update-prs | Update existing open PRs instead of creating new PRs |
 
 ## GitHub API secondary rate limit
 
diff --git a/composer.json b/composer.json
index aee3979..88b0f89 100644
--- a/composer.json
+++ b/composer.json
@@ -1,10 +1,11 @@
 {
     "require": {
-        "php": ">=7.4",
+        "php": ">=8.1",
         "symfony/console": "^6.3",
-        "symfony/process": "^6.3"
+        "symfony/process": "^6.3",
+        "panlatent/cron-expression-descriptor": "^1"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.5"
+        "phpunit/phpunit": "^9.6"
     }
 }
diff --git a/funcs_scripts.php b/funcs_scripts.php
index 7735e1c..37c108b 100644
--- a/funcs_scripts.php
+++ b/funcs_scripts.php
@@ -108,14 +108,30 @@ function rename_file_if_exists($oldFilename, $newFilename)
 function module_is_recipe()
 {
     global $MODULE_DIR;
-    if (strpos('/recipe-', $MODULE_DIR) !== false
-        || strpos('/silverstripe-installer', $MODULE_DIR) !== false
+    if (strpos($MODULE_DIR, '/recipe-') !== false
+        || strpos($MODULE_DIR, '/silverstripe-installer') !== false
     ) {
         return true;
     }
     return false;
 }
 
+/**
+ * Determine if the module being processed is something installed on a website e.g. gha-*
+ *
+ * Example usage:
+ * module_is_not_for_cms()
+ */
+function module_is_not_for_cms()
+{
+    global $MODULE_DIR;
+    return strpos($MODULE_DIR, '/gha-') !== false
+        || strpos($MODULE_DIR, '/developer-docs') !== false
+        || strpos($MODULE_DIR, '/vendor-plugin') !== false
+        || strpos($MODULE_DIR, '/eslint-config') !== false
+        || strpos($MODULE_DIR, '/webpack-config') !== false;
+}
+
 /**
  * Determine if the module being processed is one of the modules in a list
  *
@@ -132,7 +148,7 @@ function module_is_one_of($repos)
         if (!is_string($repo)) {
             error('repo is not a string');
         }
-        if (strpos("/$repo", $MODULE_DIR) !== false) {
+        if (strpos($MODULE_DIR, "/$repo") !== false) {
             return true;
         }
     }
@@ -192,3 +208,14 @@ function human_cron(string $cron): string
     $str = preg_replace('# (AM|PM),#', ' $1 UTC,', $str);
     return $str;
 }
+
+/**
+ * Creates a predicatable random int between 0 and $max based on the module name to be used with the % mod operator
+ */
+function predictable_random_int($max): int
+{
+    global $MODULE_DIR;
+    $chars = str_split($MODULE_DIR);
+    $codes = array_map(fn($c) => ord($c), $chars);
+    return (10000 + array_sum($codes)) % $max;
+}
diff --git a/funcs_utils.php b/funcs_utils.php
index 1306dfd..e5027bd 100644
--- a/funcs_utils.php
+++ b/funcs_utils.php
@@ -34,7 +34,7 @@ function write_file($path, $contents)
     }
     $dirname = dirname($path);
     if (!file_exists($dirname)) {
-        error("Directory $dirname does not exist");
+        mkdir($dirname, 0775, true);
     }
     $contents = trim($contents) . "\n";
     file_put_contents($path, $contents);
@@ -67,12 +67,39 @@ function supported_modules($cmsMajor)
             'account' => explode('/', $ghrepo)[0],
             'repo' => explode('/', $ghrepo)[1],
             'cloneUrl' => "git@github.com:$ghrepo.git",
-            'branch' => max($module['branches'] ?: [-1])
         ];
     }
     return $modules;
 }
 
+/**
+ * Hardcoded list of unsupported modules to standardise
+ * 
+ * This will only be included if the $cmsMajor is the CURRENT_CMS_MAJOR
+ */
+function extra_modules()
+{
+    $modules = [];
+    // iterating to page 7 should be enough to get all the repos well into the future
+    for ($i = 0; $i < 7; $i++) {
+        $json = github_api("https://api.github.com/orgs/silverstripe/repos?per_page=100&page=$i");
+        foreach ($json as $repo) {
+            $ghrepo = $repo['full_name'];
+            // include gha-* repos
+            if (strpos($ghrepo, '/gha-') === false) {
+                continue;
+            }
+            $modules[] = [
+                'ghrepo' => $ghrepo,
+                'account' => explode('/', $ghrepo)[0],
+                'repo' => explode('/', $ghrepo)[1],
+                'cloneUrl' => "git@github.com:$ghrepo.git",
+            ];
+        }
+    }
+    return $modules;
+}
+
 /**
  * Returns a list of all scripts files to run against a particular cms major version
  */
@@ -169,6 +196,8 @@ function github_token()
  */
 function github_api($url, $data = [])
 {
+    // silverstripe-themes has a kind of weird redirect only for api requests
+    $url = str_replace('/repos/silverstripe-themes/silverstripe-simple', '/repositories/3712566', $url);
     $token = github_token();
     $jsonStr = empty($data) ? '' : json_encode($data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
     $ch = curl_init($url);
@@ -265,12 +294,38 @@ function branch_to_checkout($branches, $currentBranch, $currentBranchCmsMajor, $
     return (string) $branchToCheckout;
 }
 
+/**
+ * Uses composer.json to workout the current branch cms major version
+ * 
+ * If composer.json does not exist then it's assumed to be CURRENT_CMS_MAJOR
+ */
 function current_branch_cms_major(
     // this param is only used for unit testing
     string $composerJson = ''
 ) {
-    // read __composer.json of the current branch
-    $contents = $composerJson ?: read_file('composer.json');
+    global $MODULE_DIR;
+
+    if ($composerJson) {
+        $contents = $composerJson;
+    } elseif (check_file_exists('composer.json')) {
+        $contents = read_file('composer.json');
+    } else {
+        return CURRENT_CMS_MAJOR;
+    }
+
+    // special logic for developer-docs
+    if (strpos($MODULE_DIR, '/developer-docs') !== false) {
+        $currentBranch = cmd('git rev-parse --abbrev-ref HEAD', $MODULE_DIR);
+        if (!preg_match('#^(pulls/)?([0-9]+)(\.[0-9]+)?(/|$)#', $currentBranch, $matches)) {
+            error("Could work out current major for developer-docs from branch $currentBranch");
+        }
+        return $matches[2];
+    }
+
+    // special logic for silverstripe-themes/silverstripe-simple
+    if (strpos($MODULE_DIR, '/silverstripe-simple') !== false) {
+        return CURRENT_CMS_MAJOR;
+    }
 
     $json = json_decode($contents);
     if (is_null($json)) {
@@ -287,7 +342,15 @@ function current_branch_cms_major(
     }
     if (!$version) {
         $version = preg_replace('#[^0-9\.]#', '', $json->require->{'silverstripe/assets'} ?? '');
-        $matchedOnBranchThreeLess = true;
+        if ($version) {
+            $matchedOnBranchThreeLess = true;
+        }
+    }
+    if (!$version) {
+        $version = preg_replace('#[^0-9\.]#', '', $json->require->{'cwp/starter-theme'} ?? '');
+        if ($version) {
+            $version += 1;
+        }
     }
     $cmsMajor = '';
     if (preg_match('#^([0-9]+)+\.?[0-9]*$#', $version, $matches)) {
diff --git a/run.php b/run.php
index e6e10a1..3090aec 100644
--- a/run.php
+++ b/run.php
@@ -72,5 +72,16 @@
         InputOption::VALUE_NONE,
         'Do not delete _data and _modules directories before running'
     )
+    ->addOption(
+        'update-prs',
+        null,
+        InputOption::VALUE_NONE,
+        'Checkout out and update the latest open PR instead of creating a new one'
+    )
     ->setCode($updateCommand);
-$app->run();
+
+try {
+    $app->run();
+} catch (Error|Exception $e) {
+    error("file: {$e->getFile()}\nline: {$e->getLine()}\nmessage: {$e->getMessage()}");
+}
diff --git a/scripts/cms-any/editorconfig.php b/scripts/cms-any/editorconfig.php
index d3ee8fa..ef52ea3 100644
--- a/scripts/cms-any/editorconfig.php
+++ b/scripts/cms-any/editorconfig.php
@@ -34,4 +34,6 @@
 insert_final_newline = false
 EOT;
 
-write_file_if_not_exist('.editorconfig', $contents);
+if (!module_is_not_for_cms()) {
+    write_file_if_not_exist('.editorconfig', $contents);
+}
diff --git a/scripts/cms5/keepalive.php b/scripts/cms5/keepalive.php
new file mode 100644
index 0000000..7c6687b
--- /dev/null
+++ b/scripts/cms5/keepalive.php
@@ -0,0 +1,34 @@
+<?php
+
+// run on a day of the month up to the 28th
+$runOnDay = predictable_random_int(27);
+// run at a random hour of the day
+$runOnHour = predictable_random_int(23);
+// run at a random minute of the hour rounded to 5 minutes
+$runOnMinute = predictable_random_int(11) * 5;
+
+$cron = "$runOnMinute $runOnHour $runOnDay * *";
+$humanCron = human_cron($cron);
+$account = module_account();
+
+$content = <<<EOT
+name: Keepalive
+
+on:
+  # $humanCron
+  schedule:
+    - cron: '$cron'
+  workflow_dispatch:
+
+jobs:
+  keepalive:
+    name: Keepalive
+    # Only run cron on the $account account
+    if: (github.event_name == 'schedule' && github.repository_owner == '$account') || (github.event_name != 'schedule')
+    runs-on: ubuntu-latest
+    steps:
+      - name: Keepalive
+        uses: silverstripe/gha-keepalive@v1
+EOT;
+
+write_file_even_if_exists('.github/workflows/keepalive.yml', $content);
diff --git a/scripts/cms5/merge-ups.php b/scripts/cms5/merge-ups.php
new file mode 100644
index 0000000..d435e32
--- /dev/null
+++ b/scripts/cms5/merge-ups.php
@@ -0,0 +1,59 @@
+<?php
+
+// run 3 days offset from when a weekly CI run is, otherwise run on a random day of the week
+$runOnDay = predictable_random_int(6);
+// run at the same hour as the weekly CI run, otherwise run at a random hour of the day
+$runOnHour = predictable_random_int(23);
+// run at the same minute as the weekly CI run, otherwise run at a random minute of the hour
+// rounded to 5 minutes
+$runOnMinute = predictable_random_int(11) * 5;
+
+if (check_file_exists('.github/workflows/dispatch-ci.yml')) {
+    $ci = read_file('.github/workflows/dispatch-ci.yml');
+    preg_match("#- cron: '(.+?) (.+?) (.+?) (.+?) (.+?)'#", $ci, $matches);
+    [$_, $minute, $hour, $day, $month, $dayOfWeek] = $matches;
+    if ($dayOfWeek !== '*') {
+        $days = explode(',', $dayOfWeek);
+        $runOnDay = ($days[count($days) - 1] + 3) % 7;
+    }
+    if ($hour !== '*') {
+        $hours = explode(',', $hour);
+        $runOnHour = $hours[0];
+    }
+    if ($minute !== '*') {
+        $runOnMinute = $minute;
+    }
+}
+
+$cron = "$runOnMinute $runOnHour * * $runOnDay";
+$humanCron = human_cron($cron);
+$account = module_account();
+
+$content = <<<EOT
+name: Merge-up
+
+on:
+  # $humanCron
+  schedule:
+    - cron: '$cron'
+  workflow_dispatch:
+
+jobs:
+  merge-up:
+    name: Merge-up
+    # Only run cron on the $account account
+    if: (github.event_name == 'schedule' && github.repository_owner == '$account') || (github.event_name != 'schedule')
+    runs-on: ubuntu-latest
+    steps:
+      - name: Merge-up
+        uses: silverstripe/gha-merge-up@v1
+EOT;
+
+// rename any existing misnamed merge-ups.yml to merge-up.yml
+if (check_file_exists('.github/workflows/merge-ups.yml')) {
+    rename_file_if_exists('.github/workflows/merge-ups.yml', '.github/workflows/merge-up.yml');
+}
+
+if (!module_is_recipe()) {
+  write_file_even_if_exists('.github/workflows/merge-up.yml', $content);
+}
diff --git a/update_command.php b/update_command.php
index 5c45c5e..f114f7a 100644
--- a/update_command.php
+++ b/update_command.php
@@ -4,6 +4,8 @@
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Command\Command;
 
+use function Symfony\Component\String\u;
+
 $updateCommand = function(InputInterface $input, OutputInterface $output): int {
     // This is the code that is executed when running the 'update' command
 
@@ -37,6 +39,9 @@
 
     // modules
     $modules = supported_modules($cmsMajor);
+    if ($cmsMajor === CURRENT_CMS_MAJOR) {
+        $modules = array_merge($modules, extra_modules());
+    }
     if ($input->getOption('only')) {
         $only = explode(',', $input->getOption('only'));
         $modules = array_filter($modules, function ($module) use ($only) {
@@ -62,39 +67,99 @@
         $repo = $module['repo'];
         $cloneUrl = $module['cloneUrl'];
         $MODULE_DIR =  MODULES_DIR . "/$repo";
+        // clone repo
+        // always clone the actual remote even when doing update-prs even though this is slower
+        // reason is because we read origin in .git/config to workout the actual $account in
+        // module_account() which is very important when setting up github-action crons
         if (!file_exists($MODULE_DIR)) {
             cmd("git clone $cloneUrl", MODULES_DIR);
         }
+        // set git remote
+        $prAccount = $input->getOption('account') ?? DEFAULT_ACCOUNT;
+        $origin = cmd('git remote get-url origin', $MODULE_DIR);
+        $prOrigin = str_replace("git@github.com:$account", "git@github.com:$prAccount", $origin);
+        // remove any existing pr-remote - need to do this in case we change the account option
+        $remotes = explode("\n", cmd('git remote', $MODULE_DIR));
+        if (in_array('pr-remote', $remotes)) {
+            cmd('git remote remove pr-remote', $MODULE_DIR);
+        }
+        cmd("git remote add pr-remote $prOrigin", $MODULE_DIR);
 
-        // get all branches
-        $allBranches = explode("\n", cmd('git branch -r', $MODULE_DIR));
-        $allBranches = array_map(fn($branch) => trim(str_replace('origin/', '', $branch)), $allBranches);
-
-        // reset to the default branch so that we can then calculate the correct branch to checkout
-        // this is needed for scenarios where we may be on something unparsable like pulls/5/lorem-ipsum
-        $cmd = "git symbolic-ref refs/remotes/origin/HEAD | sed 's@^refs/remotes/origin/@@'";
-        $defaultBranch = cmd($cmd, $MODULE_DIR);
-        cmd("git checkout $defaultBranch", $MODULE_DIR);
-
-        // checkout the branch to run scripts over
-        $currentBranch = cmd('git rev-parse --abbrev-ref HEAD', $MODULE_DIR);
-        $currentBranchCmsMajor = current_branch_cms_major();
-        $branchToCheckout = branch_to_checkout(
-            $allBranches,
-            $currentBranch,
-            $currentBranchCmsMajor,
-            $cmsMajor,
-            $branchOption
-        );
-        if (!in_array($branchToCheckout, $allBranches)) {
-            error("Could not find branch to checkout for $repo using --branch=$branchOption");
+        if ($input->getOption('update-prs')) {
+            // checkout latest existing pr branch
+            cmd('git fetch pr-remote', $MODULE_DIR);
+            $allBranches = explode("\n", cmd('git branch -r', $MODULE_DIR));
+            // example branch name: pulls/5/module-standardiser-1691550112
+            $allBranches = array_map('trim', $allBranches);
+            $allBranches = array_filter($allBranches, function($branch) {
+                return preg_match('#^pr\-remote/pulls/[0-9\.]+/module\-standardiser\-[0-9]{10}$#', $branch);
+            });
+            if (empty($allBranches)) {
+                warning("Could not find an existing PR branch for $repo - skipping");
+                continue;
+            }
+            // sort so that the branch with the highest timestamp goes to position 0 in the array
+            usort($allBranches, function($a, $b) {
+                return (substr($a, -10) <=> substr($b, -10)) * -1;
+            });
+            $branchToCheckout = $allBranches[0];
+            $branchToCheckout = preg_replace('#^pr\-remote/#', '', $branchToCheckout);
+            $prBranch = $branchToCheckout;
+            $allPRs = github_api("https://api.github.com/repos/$account/$repo/pulls?per_page=100");
+            $allPRs = array_filter($allPRs, function($pr) use($prBranch) {
+                 return $pr['title'] === PR_TITLE && $pr['head']['ref'] === $prBranch && $pr['state'] === 'open';
+            });
+            if (count($allPRs) < 1) {
+                warning("Could not find an existing open PR for $repo for branch $prBranch - skipping");
+                continue;
+            }
+        } else {
+            // get all branches
+            $allBranches = explode("\n", cmd('git branch -r', $MODULE_DIR));
+            $allBranches = array_map(fn($branch) => trim(str_replace('origin/', '', $branch)), $allBranches);
+
+            // reset to the default branch so that we can then calculate the correct branch to checkout
+            // this is needed for scenarios where we may be on something unparsable like pulls/5/lorem-ipsum
+            $cmd = "git symbolic-ref refs/remotes/origin/HEAD | sed 's@^refs/remotes/origin/@@'";
+            $defaultBranch = cmd($cmd, $MODULE_DIR);
+            cmd("git checkout $defaultBranch", $MODULE_DIR);
+
+            // checkout the branch to run scripts over
+            $currentBranch = cmd('git rev-parse --abbrev-ref HEAD', $MODULE_DIR);
+            // ensure that we're on a standard next-minor style branch
+            if (!ctype_digit($currentBranch)) {
+                $tmp = array_filter($allBranches, fn($branch) => ctype_digit($branch));
+                if (empty($tmp)) {
+                    error('Could not find a next-minor style branch');
+                }
+                $currentBranch = max($tmp);
+                cmd("git checkout $currentBranch", $MODULE_DIR);
+            }
+            $currentBranchCmsMajor = current_branch_cms_major();
+            $branchToCheckout = branch_to_checkout(
+                $allBranches,
+                $currentBranch,
+                $currentBranchCmsMajor,
+                $cmsMajor,
+                $branchOption
+            );
+            if (!in_array($branchToCheckout, $allBranches)) {
+                error("Could not find branch to checkout for $repo using --branch=$branchOption");
+            }
         }
         cmd("git checkout $branchToCheckout", $MODULE_DIR);
 
+        // ensure that this branch actually supports the cmsMajor we're targetting
+        if (current_branch_cms_major() !== $cmsMajor) {
+            error("Branch $branchToCheckout does not support CMS major version $cmsMajor");
+        }
+
         // create a new branch used for the pull-request
-        $timestamp = time();
-        $prBranch = "pulls/$branchToCheckout/module-standardiser-$timestamp";
-        cmd("git checkout -b $prBranch", $MODULE_DIR);
+        if (!$input->getOption('update-prs')) {
+            $timestamp = time();
+            $prBranch = "pulls/$branchToCheckout/module-standardiser-$timestamp";
+            cmd("git checkout -b $prBranch", $MODULE_DIR);
+        }
 
         // run scripts
         foreach ($scriptFiles as $scriptFile) {
@@ -105,42 +170,49 @@
             eval($contents);
         }
 
-        // set git remote
-        $prAccount = $input->getOption('account') ?? DEFAULT_ACCOUNT;
-        $origin = cmd('git remote get-url origin', $MODULE_DIR);
-        $prOrigin = str_replace("git@github.com:$account", "git@github.com:$prAccount", $origin);
-        // remove any existing pr-remote - need to do this in case we change the account option
-        $remotes = explode("\n", cmd('git remote', $MODULE_DIR));
-        if (in_array('pr-remote', $remotes)) {
-            cmd('git remote remove pr-remote', $MODULE_DIR);
-        }
-        cmd("git remote add pr-remote $prOrigin", $MODULE_DIR);
-
         // commit changes, push changes and create pull-request
         $status = cmd('git status', $MODULE_DIR);
         if (strpos($status, 'nothing to commit') !== false) {
             info("No changes to commit for $repo");
+            continue;
+        }
+        cmd('git add .', $MODULE_DIR);
+        if ($input->getOption('update-prs')) {
+            // squash on to existing commit
+            $lastCommitMessage = cmd('git log -1 --pretty=%B', $MODULE_DIR);
+            if ($lastCommitMessage !== PR_TITLE) {
+                error("Last commit message \"$lastCommitMessage\" does not match PR_TITLE \"" . PR_TITLE . "\"");
+            }
+            cmd("git commit --amend --no-edit", $MODULE_DIR);
         } else {
-            cmd('git add .', $MODULE_DIR);
+            // create new commit
             cmd("git commit -m '" . PR_TITLE . "'", $MODULE_DIR);
-            if ($input->getOption('dry-run')) {
-                info('Not pushing changes or creating pull-request because --dry-run option is set');
-            } else {
-                // push changes to pr-remote
-                cmd("git push -u pr-remote $prBranch", $MODULE_DIR);
-                // create pull-request using github api
-                // https://docs.github.com/en/rest/pulls/pulls?apiVersion=2022-11-28#create-a-pull-request
-                $responseJson = github_api("https://api.github.com/repos/$account/$repo/pulls", [
-                    'title' => PR_TITLE,
-                    'body' => PR_DESCRIPTION,
-                    'head' => "$prAccount:$prBranch",
-                    'base' => $branchToCheckout,
-                ]);
-                $PRS_CREATED[] = $responseJson['html_url'];
-                $REPOS_WITH_PRS_CREATED[] = $repo;
-                info("Created pull-request for $repo");
-            }
         }
+        if ($input->getOption('dry-run')) {
+            info('Not pushing changes or creating pull-request because --dry-run option is set');
+            continue;
+        }
+        // push changes to pr-remote
+        // force pushing for cases when doing update-prs
+        // double make check we're on a branch that we are willing to force push
+        $currentBranch = cmd('git rev-parse --abbrev-ref HEAD', $MODULE_DIR);
+        if (!preg_match('#^pulls/[0-9\.]+/module\-standardiser\-[0-9]{10}$#', $currentBranch)) {
+            error("Branch $currentBranch is not a pull-request branch");
+        }
+        cmd("git push -f -u pr-remote $prBranch", $MODULE_DIR);
+        // create pull-request using github api
+        if (!$input->getOption('update-prs')) {
+            // https://docs.github.com/en/rest/pulls/pulls?apiVersion=2022-11-28#create-a-pull-request
+            $responseJson = github_api("https://api.github.com/repos/$account/$repo/pulls", [
+                'title' => PR_TITLE,
+                'body' => PR_DESCRIPTION,
+                'head' => "$prAccount:$prBranch",
+                'base' => $branchToCheckout,
+            ]);
+            $PRS_CREATED[] = $responseJson['html_url'];
+            info("Created pull-request for $repo");
+        }
+        $REPOS_WITH_PRS_CREATED[] = $repo;
     }
     output_repos_with_prs_created();
     output_prs_created();