Okei, so as we know, 4 is the maximum numer that we can get into flashpoints and/or groups + heroic quest zones.
I stumbled upon a bug that will let you summon companions even if you're grp is full. This way, you can use your companions to help you complete the mission.
Here's how you do it: Get a grp with the people you want to do it with. You will have to be more than two players for this to work. This is because you can only summon one companion at one time.
Grp with more than two players.
Log out
Have them summon their companions
Log back in.
You will be kicked from the group, but you will still be inside there with them. Making you able to finish the quest, loot, interact with the quest objective.
So good luck. Its not very needed, but if you are struggeling, it may be helpful.
- Alkzn