Current party size (4) is a tad bit small. When you get some cool people who aren't in your party, but you still team up with them things can get confusing.
Since there are no rules against teaming, I don't think there should be a cap to the total party size at all. While obviously, forming a party makes things a lot easier (like identifying friend from foe + group chat), having it capped will and has already lead to some players just being excluded from the fun, especially if they die.
There's two ways to handle this: Either increase cap to a much higher amount (5-9) o