Can i add newly pumped breastmilk to already refrigerated breastmilk?

Only after: You can add them together only after you have cooled down the newly pumped milk to refrigerator temperature. You should not add warm milk to chilled milk and never to frozen milk as it can promote bad bacterial growth. Once cooled down, though, can be combined to one bottle. Make sure you mark dates so you use before the oldest component goes bad.

Nope: This is not recommended. Keep your dates distinct.