Hair products for african american children!!?

My kids are 3 and 4 and I am having a very difficult time searching for the right stuff. I've tried Carol's Daughter, Kinky Curly- those made their hair more dry, frizzy, and crunchy. I also used Care Free Curl, which worked the curls were definitely popping but it made their hair greasy overtime :( I just recently tried John Frieda Dream Curls. It was great when wet but it dried they hair frizz, and was soft but the curls weren't popping. I even added a ill hair polished from fantasia Please, please help what products do you suggest. Their hair Is 3b, 3c and maybe 4a,this is a guess. My oldest daughter the curls are tight in the front, the middle looks sort of wavy I guess and some parts of their hair has big curls. My youngest daughter curls are about the same but mostly has tight curls when wet. They both have really thick kinky hair. I don't know what to do!!! HELP!!!