joining several directories into a single one, then replicating it

Hello,

We are in the process of merging several universities into a single one. As we are working on the authentication part, we already test some solutions. We put a server as a replica of our three directories, then two other replicas from this one. It works but I am not sure this is the best solution.

Is it better to put a back-meta ou back-relay server for relaying data, then replication from this one? Also, if we put all data into a single one as we did, what happens if we have the same entry-uuid?

Thanks in advance

Dom