The Frontosas are gentle giants and yet they do feed on smaller fish but I hope they leave the smaller ones alone.
I am a bit sceptical about the leleupi and brichardi housing and breeding together.
"The diet of Cyphotilapia frontosa is mainly composed of shellfish and smaller fish. However, when kept in an aquarium they will eat almost anything, from vegetable flakes to other fish and insects (Brichard 1989; Axelrod 1993)." http://animaldiversity.ummz.umich.edu/accounts/Cyphotilapia_frontosa/
I used to keep frontosas with paracyprichromis nigripinnis. It worked fine for quite a few years. Then one day, the nigripinnis started to disappear. Eventually the frontosas ate them all.