This would also be great if in LDAP System is used like DirX which allows to have a Forest of LDAP Domains (per location) which are combined to one general for the company (which can't be used for placing requests).
From ZF perspective this idea is outdated and it could be closed.
Meanwhile we have a working multiple LDAP solution in place. This solution is based on the support article mentioned in the previous comment in scenario 1.