Parties over 6 are different. You will require assistance from a CM. When we met up with friends during our last trip, we actually did exactly this. I'm pretty sure we could see our entire party of 9 but we couldn't add more than 6 total (
DAS holder + 5 companions) to a single return time. We had assistance from a Blue Tent CM when we were linking our friends that day. So that may have been why we could see everyone. Or if it was because DD had 4 people linked to her and DS had the others linked to him. Neither has their own
MDE, they are both under mine.
When we were booking return times we used mine and DH's MDE's. I booked DD's plus 4 companions (5 total). DH booked DS's plus the other 3 companions (4 total). We did this simultaneously as we were standing together so we got the same return times and we made sure that we were only selecting certain people. Again, I don't know if we were supposed to be able to see all 9 people or not, the CM may have given us pixie dust that day.
If you can't see your whole party, you will have to use 2 MDE's similarly as to what we did. I would have two separate devices to do this. It made it a lot easier.