Hi Martyn
Looking through the Library we use to make the LDAP query there is an option input for Scope that supports the following:
ScopeBaseObject = 0
ScopeSingleLevel = 1
ScopeWholeSubtree = 2
Currently its set to 0 and this is not configurable, i have raised a Change CH00138411 to expose the full set of search options, would being able to query the whole sub tree negate the requirement for you to search multiple DSN's?
Kind Regards
Trevor