When you update an address in NXT it should update all records and relationship records that share that address. This however is not the case and is causing tons of returned mail. Same should apply when marking an address inactive. If you mark an address inactive it should make all records and relationship records that share that address inactive as well.
I see a list of all persons who share an address and have the option to update the shared address or just the single address. We use this frequently when updating mailing addresses for Alumni who no longer live with their parents.