I haven't played multiplayer yet, as I haven't found any open sessions so far, but I will still second this. And to give an example, even though nowadays it is no longer that good of an example, please look at Star Wars: The Old Republic and its multiplayer dialogue system.
There, when a player clicks a quest NPC it will bring up a queue instead of going to the conversation right away. It'll also display a radius around the NPC, which other players need to enter, if they want to take part in the conversation. If they do, all players, that took part will see the conversation and if a player choice comes up, a dice roll will decide, which of the players gets to answer. The consequences of the conversation get decided by the player, who got to answer, but independendly of that every player gets the results of their respective choice (like alignment changes in case of SWTOR). What matters is the intention, so to speak.
I already consider BG3 a worthy successor of the series, but I am really, really hoping that multiplayer will be more than just one player following the story and the other three being reduced to combat backup. That's basically what the original series was like. BG3 is different however. In BG1 and 2 the host was Gorion's ward and the other players were basically henchmen. In BG3 everyone will start with the same problem, effectively making them equal. It would be so very cool if this could be reflected in dialogue as well. The origin characters can be recruited as companions and all of them have an oppinion on the players behaviour and would pick dialogue choices according to their personality, if they weren't just pre-written, AI controlled characters. A party of four humans should be able to do the same. This is a role playing game after all and I for one would like to role play my character with friends or even strangers. Being able to do so in dialogue is what D&D would allow you to do.
I hope that such a thing is possible for BG3 as well.
Last edited by Kasai; 12/10/20 11:04 PM. Reason: typos
