cedar shore
When in duos, it would be very convenient to have a party chat between you and your partner. While you can dm them, it is an additional step and the partner does not see the dm (no notification until after the game, etc).
The chat on the left could have a toggle that allows you to switch between room and party chat, as well as allowing a separate keybind to focus the party chat.
leaden monolith
When in duos, it would be very convenient to have a party chat between you and y...
what? 
isn't automatically applied during QP2, and they have to be 
or 
to receive invites
that said, your party member is highlighted purple and automatically announced (to you, meaning their messages are stickied to the bottom) in ingame chat. i totally understand why you wouldn't want your communications to be public knowledge, but it's still harmlessly easy (and less guaranteed for them to see than DMing them, since they can actually tangibly hide chat ingame)
cedar shore
I have played rounds where no dms show up on the bottom right during a qp game but they show up in the tab panel after the game when I check
this doesn't seem like a huge priority for now, but if party mode ever expands outside of quick play I think it would be significantly more important
leaden monolith
i haven't