It sounds like she is doing all the right things, especially mixing the breast milk and formula. It is probably nothing to do with the type of formula -- all three of my kids transitioned to Similac. What you don't mention is who is one trying to get the baby to drink the formula. If it is your friend, then that is probably the problem. Baby expects breast milk from Mommy and won't take anything else. Instead, another adult needs to do it (Daddy, Grandma, babysitter) and while they are doing this your friend needs to disappear -- baby should not be able to see or hear Mommy (or smell, for that matter!). And even then baby will still fight it. But don't give in -- trust me, the baby won't starve (even though she'll be crying mad!). I just had my husand and MIL put the bottle aside for 15-20 minutes, then try again. It worked with all three of my kids. After a couple of days they became more accepting. Then we gradually decreased the amount of breastmilk in the mixture -- about a week later it was all formula!