This comes from my personal experience on three different cruises, I think some people who responded to this thread have not personally experienced this process. We have always been permitted to board together with the other people in our linked reservations, but only with the latest boarding number. Although I have asked all three times, the group with the later PAT, has not been able to board with the earlier groups. So, if you wish to all board together you may, but I would guess it will be with the latest boarding number. Really the only reason to do that is if you all wanted to take a boarding picture together. Otherwise, it might be nice for the people who board first to find a nice lunch table, or stake out an area by the pool where the later arrivals can meet them.