I think it can be solved with a two step process. First, the mods of the community and only them can make a request to move from instance A to instance B, and second, the admins or mods of instance B approve the request, importing only the posts and comments from federated users.
I think it can be solved with a two step process. First, the mods of the community and only them can make a request to move from instance A to instance B, and second, the admins or mods of instance B approve the request, importing only the posts and comments from federated users.