If you are linked on MDE, then you'll be able to see any photos that are linked to their magic bands as long as they have their settings made to allow friends to view the pictures. So, any ride photos that are linked to at least one band from their group will be visible to you as well. If you want pictures from a photopass photographer to be visible, but you want a few pictures included that are only your family, just make sure that one of the other family's magic bands gets scanned for those pictures and they will show up.
One other thing to keep in mind with those ride photos: if your family and the other family end up not riding something together that does pictures, you might want to borrow one of their bands for the ride so that your family's picture will show up.
Does that make sense? I feel like I'm rambling lol