#throuple fics

I read a fic like five years ago and I’ve been struggling to find it. Sherlock, John, and Mary are a throuple (and it didn’t put me off because I hate Mary) and I think it was molly(?) that stops in to get something (?) and when she enters the flat, John was wearing Sherlock’s clothes (?) so she puts together what is going on… and I think Mary invites her to watch Sherlock and John get down to business, and when they finish sherlock and her have a go. Ring any bells?