MZ

My question is related to Bob's. If you are able to use one (1) call sign for the whole family. How do you call each unit or family member on air? Do you just mention your callsign then say.."unit 1" or unit 2" to be able to call which ever unit you are trying to contact? Or do you use callsigns something like what CBers use? meaning they can have any other kind of callsign just to be able to designate each unit?