I believe i’ve read that in a future release you’ll allow entities to be created from different databases. Do you have an ETA on this version?
If it’s a long way away, what is the best way to add a couple extra databases that will be the easiest to migrate over once the release goes live?
Yes, it was discussed here.
This is the work in progress (see for example this commit on GitHub) and as promised it will be available in the beginning of September.