N.A.
We went through the same thing! My daughter went through the hard BM's even when mixing cereal in her formula for her feedings before bedtime. I switched her over to oatmeal and it has been so much better! Her BM's are different than when she was exclusively on formula but they are by no means "hard". Try the oatmeal and see how it works... Remember to get just plain oatmeal though. I haven't tried the oatmeal with bananas, but I have heard that bananas are binding too and that may create harder BM's again.