My baby is having hard stool after I give him stage 2 fm. Can I alternate between stage 1 and stage 2 fm? Can we start to introduce stage 2 fm after baby is 10 months old?

To me, I think all FM is almost the same. Of cos, when U start trying, always mix it to see if it works for your child before switching it completely. I don't foresee any issue to start stage 2 FM at ard 10 mths old. For some FM in the past, only got stages 1 and 2 and of cos, people will stick to stage 2 until the kid is totally wean off from FM unlike now, there are so many stages available.