Mackenzie didn't have refulx but did vomit her fomula up so my MCHN suggested we try the HA-AR formula - worked wonders for us. No more vomiting. We premade them up and then warmed them in boiling water when we were ready to use and then when the light came on in our heads we just put the sterilised cold water in the fridge in the bottles and then added the boiling water to make up the bottle and added the formula. I also had to make the hole in the teats bigger as it was taking her too long to feed (40 mins) and once I did that it was only taking 10 minutes.