I don't think there is any difference between soft ice cream and hard ice cream. Any dairy can constipate you especially cheese. Have you had here tested for food allergies? My daughter had bowel issues (along with several other issues) and she ended up having a milk allergy. Just a thought, but if she can eat soft icecream she should be able to eat hard ice cream. Has she eaten anything else with it or before it that could actually be causing the issue? Keep a food diary, it helps A LOT when you are trying to figure out a digestion issue.