Combine entities from several replicated databases to one database

[Andrey Cherepanov]

There are a dozen branches in which add and modify users in LDAP. There
is central office in which will plan make joint addressbook with branch
data.

I know that replication works only with database. I can replicate all
branch database to central office. But I don't find way to join entities
to one database by ridht way. Anybody do it?