A.M.
Hi there,
I've never heard of adding the thickener to formula, but I do use it regularly in my practice as a speech therapist with my patients. The reason we add it to patient's liquids is to make the liquid more managable to swallow. What about adding rice cereal to thicken your daughter's bottle instead? Have you asked your ped? What is his/her advice? If you do add it, just be careful with the measurements, b/c the longer the thickener sits in a liquid, the thicker and thicker it becomes. Good luck!