They say you shouldn't blend formulas... but my maternal nurse said it wasn't so bad what I did. She said AR & the normal formula are the same, but AR has an extra ingredient that thickens it up.

My son wasn't a bad vomiter... but bad colic.
I would put one third AR formula to two thirds normal formula.
ie: in a 180ml bottle I would put one scoop of AR and two scoops of normal formula.
This was the SAME BRAND though.

It seemed to work well for my son. It thickened it up, without being too thick.

I heat his bottles a little bit to take the chill off them (as I used chilled boiled water). But he has never liked really warm water.

I only recently stopped doing this when all the "gold" formula went on special. But he is 5 months old now and his stomach has really settled.