my 3 year old has regular constipation. she is also small, 30 lbs, so it is hard to feed her high fiber foods that help her constipation and still allow her to gain weight. when she eats high fiber foods, she won't eat as much as she should and therefore doesn't gain weight. to add to the trouble, i give her nutritional drinks to help her gain weight cause she is so picky. could i start mixing some benefiber with her milk and help her get fiber that way?