subnetwork flag to use network/subnet outside the project where dataflow runs in

[bujiazhang]

I am trying to run the vcf_to_bq pipeline using a subnetwork that outside the project where dataflow runs in, but even though I set the full path of the subnetwork flag, it still goes to the project where the dataflow runs in to find the subnet. The subnetwork I am using is from a shared VPC, that's why it's from different GCP project.
Is there anyway to set up the subnetwork to use the specified full path instead of using the project where dataflow runs in?

Thanks!