Does a mailbox's explicit membership of a collection over-ride its membership in another collecti (4263544)

A collection has been populated using either containers/OUs or a distribution group. There is a requirement to process in a separate collection a mailbox which is in this existing collection by virtue of it being either located in the relevant container or a member of the relevant distribution group. A mailbox can not be processed in two separate collections, so will its explicit membership of another sync collection over-ride its membership via container or distribution group?

Yes, explicit membership of a collection will over-ride membership in another collection.