I wouldnt mix shell dwellers with Mbunas. Some people mix bigger Tanganyikans but I wouldnt recommend it. I think the Malawis would just be too much for the smaller shell dwellers. @connorlindeman is right with more Tanganyikans like Cypichromis or Brichardi would be good, some of the bigger Lamprologus species would be ok too like Caudopunctatus. Even other shellies like Occellatus Gold might be nice?