Is there a way to edit a polygon's vertices individual coordinates or attach multiple polygons to an image?

[kujukuju]

I'm looking for a way to make something this picture:

There are 3 different types or layers of lines attached to 1 image. This imagine combined with its polygons is then ideally converted into a library object.

As far as I can tell you can only have 1 layer attached to each image. To make the desired effect I've Created a CompositeItem that contains a CompositeItem that contains a CompositeItem that contains the image. Each of these CompositeItems has it's own polygon, and so I defined each layer through the layer of CompositeItems.

My questions are:

1. Is there a better way to add multiple polygons to an image and save it as a library asset? I'd need some way to either label or distinguish the individual polygons.

2. Is there a way to edit the exact coordinates of a polygon vertex? For my game engine it's crucial that some of the vertices overlap perfectly onto the same point, so I'd need to either be able to manually enter the coordinates of a vertex or snap the vertices to something in such a way that I can be sure they have the same coordinates.

Is any of this possible with the overlap editor? I'd love any help on this, I've been searching for a while without any luck. It also sucks that I learned the overlap website was recently hacked and thus is down right now. :(

Thanks!

[kujukuju]

To add onto this:

3. I'm also looking for a way to just draw a simple line, label it, and edit the vertex coordinates of the line. I can't figure out how to do more abstract things like this.