Welp, tried again the unofficial fix to expand the party to six with the new patch (7), I found the NEW placement for the string to edit, but now the game crashes 100% of the times for me when the tweak is applied.
Guess there's no way around playing with 4 characters now.

Party control in Baldur's Gate 3 is a complete mess that begs to be addressed. SAY NO TO THE TOILET CHAIN