Allegedly support for "party-wide dialogue UI" is in development.
Still not sure if this will ever address NPCs picking randomly on who they start the conversation with, specifically.
This was a big thing in dos2 as well and unlike other story issues this one seems like merely a question of scripting, so I really don't understand how come they moved on to a new game and still didn't fix it, unless it's intentional. The only other possible explanation is that maybe multiplayer makes it more complicated to fix. Anyway there is no reason for it to keep happening. Just have a "main character" flag on your MC that makes NPC initiate dialogue only with him. They only have this kind of mechanic when talking to companions (you can't make a companion talk with another companions, the game will change to your MC when you try it)
