I've kept the following mbuna with peacocks and haps in a 100 gallon without problems. But the peacocks didn't breed easily. Peacocks were Stuartgranti Maleri (pair), Stuartgranti HB red shoulder (1m/2f), Jacob (otter point) pair, 1 Eureka Red male,haps were red empress 1m/3f, pair o. lithobates, 1 m borleyi red fin, 1 m venustus, 1m/2f C. moori. If your dominant mbuna group has enough females, your mbuna should fall under his control. It worked out that my caillanos chased his 3 females mostly, and the other mbuna just enough to keep them in line, while almost never bothering the haps/peacocks, that was the red empress males job (who spends most of his time chasing his 3 females)
M. Callainos
P. Acei
L. Caureleus
M. Greshaki
P. Acei
M. Pyrsonotos (or very similar zebra)
L. Sp. 'hongi'
all but the callainos were pretty mellow, and even then the 100 gallon provided the male enough room to be the boss.