Re-chill unused EBM

Hey guys, need your advise. My 3mth baby recently increased from 60ml to 100-120ml. However some of the milk I have expressed previously is up to 85ml. Can I warm up 2 bags to make up to 120ml and put the remaining milk back into the fridge? For instance I have 1 bag of 60ml and the other is 85ml. I need to mix them and instead of dumping the remaining 25ml, I chill it back. Those milk bags are frozen by the way hence I will need to thaw them first.