It's great to find out that GV's are possible at 7 months out. Owning at a DVC that doesn't have GVs is a bummer when planning for large get togethers.
We will have 13 total: me, DH, Mom, Sis, BIL, Niece (she's not due until February 5th), Niece 13, Niece 15, DD (11), DD (26), future Son-In-Law, DS (22) and his girlfriend.
We have all traveled together before and everyone gets along really well. The secret for us is that there is no set schedule other than which park we will be in each day and then everyone just meets up at their convience.