When I spoke to the group ticket sells department last week she said that if there is enough demand, they will open up 3 more sections on the opposite side of the stadium for group sales, sections 225 to 227 I believe she said, sometime in July. They have a list currently of people wanting group tickets, you must purchase at least 20.
I purchased my tickets in round one and was able to purchase more a couple days later. She made it sound like I could purchase more since I already have purchased the minimum.