From what I have gotten from the AMA we will only have 4 members at a time in the party do to only having 8 companions but that might change so we will have to just wait and see what happens in BG3
Cthulhu: FOR THOUSANDS OF YEARS I LAY DORMANT, WHO HAS DISTURBED MY- Oh its you... Warlock: Greetings my lord- Cthulhu: LET ME SLEEP-