We had 4 in one section, 5 in another, and tied to pick up 4 seats that opened up right behind a few rows. It put us at 13 so it wouldn't allow it. We called the ticket office and they wouldn't allow the extra ticket. Then we tried to just buy the three tickets and it wouldn't because it left 1 seat open. We ended up dropping one of the 5 in the other section and buying all 4 of the new ones. So we left one open this year.

I dont know why the system would allow us to drop 1 and leave it open but not leave one open when wanted to buy. But it worked.