To straighten or not to straighten...

Does anyone (preferably African American) know whether or not it'd be okay for me to use flat irons to straighten my 1 1/2 year old dd's hair? I feel like it's a bad idea, but her hair is so unmanageable. It's super curly and tangles too easily. Literally every time I try to comb or brush it, it gets knotted and comes out in clumps!