Ok i have a question, how come everything i've read says to only combine fresh milk for 24 hrs, but you can add cooled milk to already frozen milk even if it's from a different day? this doesn't make much sense to me. I know these are just guidelines, and i put different days milk together in the fridge, and it seemed fine before (i don't any more). also, you moms that are using the ice cube trays, what are you defrosting the milk in? do the cubes fit into a bottle? is that safe, knowing that some plastics (ex:from ice cube tray) leach into foods? (yes, i know baby bottles are plastic, but supposedly they are safe, no pvp or whatever) just wondering. thanks!