Just ran a test, yes it appears you can add --network as well as org and then it works.
Only issue I have with that is I need to keep a flycast ipv6 for each app, and clean them up when I clean up the app’s… not the end of the world… still impressed by what you can do with Fly.
I might try and see if custom networks can access items in the org’s default network, and then I can just re architect a little around that…