virtually merging objects under a single DIT

I'm hoping to support an administrator of an application who would like to authenticate users that may exist in one of multiple LDAP sources. The application can provide a single base DN, username, and password.

I can get close by using database ldap and rwm to rewrite the base of multiple sources to a common one:

ou=DC Users 1,dc=proxy,dc=myorg,dc=org

ou=DC Users 2,dc=proxy,dc=myorg,dc=org

But I'd like to go a step further and present user objects from both sources under a single suffix point like:

ou=DC Users 1 and 2,dc=proxy,dc=myorg,dc=org.

Is there a way to virtually merge / flatten the structure from multiple sources?

Thank you,

Dave