A few months is not going to cut it, a 10 gal tank is just way too small. You need to take these fish back. When you get your new tank, then you can work with African Cichlids. They can be quite aggressive to each other and in that size of tank they are just going to end up killing each other off.
It takes a little research to find the perfect mix to have a peaceful Malawi tank. First off they like to be in groups, so you need 6 - 8 of each species. In a 75 gal tank you can have 4 - 6 different species groups, depending on what you pick. You want to be sure each group has their own area of the tank and that they don't have to compete with the other species. It think it is best to pick the one you like the best and the build your tank around them. I would be glad to help when you get your new tank set up.