Unless they're wild caught or possibly F1's you can mix Africans and New World cichlids. I've done it for years with no problems. I'd just make sure that they come from the same water params wherever you buy them and they are the same temperament.
I had my Jewel living with a Green Severum and Jack Dempsey until recently. I have moved the Jewel in with my newer, much smaller Africans now. But there were no problem with the Jewel cohabitating with the other 2.
