Evidently, someone found a way to exceed the party size limit:

i remember a few weeks ago, there was one in ToA forming a group to UW.
he wrote an exploit that would alow an over sized party.Meanigng if you download his little exploit you should load in a map with 8 humans and each would have 3 heros, for a party of 32/8. This kid got us all on vent, and proved that his exploit worked but mapping out and loadn in with his own extra 3 heros to make the party11/8,and then gave the link once everyone was all fascinated by how he did that.. i did not trust it so i asked question.

Not a whole lot of information is known about the exploit but you can read about it on this thread. And the corresponding game update here.

What is the Hardest thing to do in every MMORPG?