Stored BM question

DD takes about 4 oz. at a feeding, DH has been feeding her one bottle of pumped milk every night.  If I have 2 pumped bottles in the fridge that total 4 oz., one I pumped 2 days ago and one pumped from today, can we combine them, warm them together, and put them into one bottle to feed her tonight? 

Also, can I thaw 2 frozen bags from different days and combine them to make one bottle?

Thanks.