Convert the User Group Field to another field

I’m refactoring a workspace to scale to different regions. I need to change the people field that is being used to a lookup from “Positions” (similar to this FR: Convert Field to Formula)

This is even more painful because I need to go through all the databases and spaces and re-share it with the new user group.

Just to be sure, is this request about converting an existing field into a different type (from user field to formula field)
Or
Changing which database Fibery considers the user group database?

Within the same database, I want to change the “Group” field (the user relation that is identified as the one in charge of grouping) to a different field. I can not make a different “Treat database as user groups”, as a different field is already user groups, and I can not disable the existing one without removing all the existing sharing.