Comming from a person with PKU i wouldn’t suggest adding any too much flavor into the formula. I’m 19 years old and what my parents did for me was, eveytime it was time for me to drink my formula, they would open the cap and have me smell it at first, just to get used to the smell. I know with your situation it is a little late for that, since there’s some gagging going on. As i started getting older, i hated the smell more and more, we tried the same thing, adding strawberry and even tried grape… YUCK..i vommited both times. Don’t try adding anything to the formula again… you should try doing what my parents did just to see if it works… dont hold it right under her nose.. just keep the top off every once in a while…im might help, it might not…but its worth a try..i know how your child feels. Good Luck !