I agree, Kribs with other cichlids is asking for trouble especially other pelvicachromis species. Kribs can be fast and they are definitely a terror once they start breeding or even if they aren't breeding and if they've already figured out their territory, they will pick at their tankmates. I'd say just leave them as they are or if you really want tankmates, get fast fish with the same temperament or are more peaceful. They will act as dithers to the Kribs. good luck
On a side note, my experience with kribensis is that once they've made their partnership, they will always stay together. If one of the fishes dies, the other one tends to sulk and loses color. It doesn't seem to be able to pair up again and will only attack any other krib that you might pair it up with. Also, I've noticed that females are a lot more dominant/aggressive than males. Maybe it was the case with 5 of my female kribs but it could be different for you.