Use the same local replica for multiple projects

[Ori]

I’ll second that this works, you can just use one project’s replica as your blockchain and deploy to that.
Related comment here:

Getting exact same canister ID's for two separate projects locally and they share ledger funds as well

You’ll only want one replica instance (dfx start) running. You can run this from any of the projects and deploy to it from the others. If you run dfx start in project A’s directory, then deploy from project A, B, C etc. they’ll all deploy to project A’s replica. All the local replica state will be stored in project A’s .dfx directory. The canister ids will still be stored in each project’s respective .dfx directory, but now they’re all deployed to one replica they’ll be given unique canister id…