L.P.
Hi K.,
I feel for your sister. My son also had reflux really bad as an infant. He was on zantac for a while and it did not help. We chose not to do anything at that point. He was still gaining weight on a regular schedule and did not seem to have too much discomfort. The good news is that they do grow out of it. I'd also suggest that she call the doctor to find out the exact way that her son should get his dosage.
L.