I dont want to offtopic with first coment, but i feel the urge to mention that 6 member party will solve this problem ...
Best answer.
I wouldn't really care being locked after act one but if I had more than 3 companions...
If I'd have to change a character to pick a mercenary for a reason or another, I'd rather do it with a party of 6 than a party of 4 to keep more companions.
Of course if there are only 7-8 possible companions in the game it's hard to increase the party size...
There are not enough companions in BG3 and we can only choose 3 of them so lock the party after act 1 will even worse than it would be in what every game called Baldur's Gate *number* should be ; a game with a party of 6 and tons of possible companions...
