Andy.
Thanks for the reply.
You can't because translucent uses back-ldap which disables lastmod, so replicating the local database is at least impossible with syncrepl.
The solution I came up with was to slapcat/slapadd when I do changes to the translucent db...
Would you mind elaborating? The slave server would have to be stopped to use slapadd?
What I find particularly puzzling is that there seems to be no recommended way of doing this. Surely if translucent overlays are used then replication of them is essential.