How to get placed with a new 2v2 partner?

[storybythethroat]

Hi! I placed with a 2v2 partner months ago, but I found I didn't like playing on a team with them. I recently found a partner I enjoy more, and I've played a couple of matches alongside them and still no placement. Can someone explain to me how qualifying matches work with 2v2 games, and how I can get a ranking with my new partner so we can start climbing (or descending! ) the leaderboards together?