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?

I read that this is quite normal. Stage 2 formula would contain more calcium and iron to meet baby's growing needs as well as his next stage of development and this, unfortunately, can lead to hard stools or even constipation. If baby is already eating solids on top of the formula milk, perhaps you can include more fibre in his diet as this can help loosen the stool a wee bit?