Hellobee Boards

If I mix the two, I mix the formula first and then add the cold breastmilk. But that's usually right before I heat them up.

Although it's a good idea, I don't think it's necessary to chill the water before you mix. As long as the bottles will be going right back in the fridge or cooler, the room temperature water shouldn't affect the chilled breastmilk.

you're only supposed to mix cold breastmilk with cold breastmilk, which is how i assumed that the same goes for room temp formula + cold breastmilk, unless you're feeding right away.

but i've been doing it wrong all these years (mixing room temp bm with cold bm) and have never had a problem. i stopped doing it though once i learned i wasn't supposed to...