Support for 6 party members already exists within the UI...why not just make it official? To prove this, all you have to do is use the multiplayer party creation to put together your own 4 players, then let Laezel and the intellect devourer join your party in the intro section. They both join the party without any issues. No "you're full up, find me when you ditch one of those losers" responses. Nothing breaks, and the system doesn't crash. For some inexplicable reason this seems to be the only portion of the game where this can happen, and it only works until you complete the helm mission. Once you're on the beach, Shadowheart refuses to join the party because reasons
Why not just increase the party size?
Also, this may be an unpopular opinion, but I really don't care about the story of the exploding wizard, grumpy cleric, grumpier warrior, vampire thief, or one-eyed warlock dude anymore. I would love it if you could make it possible to create 100% custom parties natively. I get that you all are putting a significant amount of time and effort into creating the pre-gen party characters you WANT us to use, but I honestly would prefer to be able to make my own
characters without dealing with all the baggage you're packing into those pre-gens. I understand that that you're trying to make an interesting story, and I have played through that story about 25 times now. I would just like to have the option to play the game the way I want without having to do some ridiculous workaround to do it. I'd like to be able to play several classes / races that I don't normally play, and I don't want to have to create a new game for each one and play through all the same content over and over and over... BG3 is an awesome game, and some of those side stories sound like they'll be very interesting once they're fleshed out, but please let me decide whether and when to engage with them.