Quoting Kansas Bonanno:" ok for me to put some milk i warmed up back in the fridge that LO didnt drink?"
Is it formula or breastmilk? Formula absolutely not, you need to use it within an hour or toss it. Breastmilk can sit out for longer but I wouldn't put it back in the fridge after being heated.
I wouldn't heat it twice in a roll .. id toss what's ever left or give it to him cold I'd think warming it up diff Times like that would cause it to spoil :-/