Yes, as long as all the milk is still within the shortest use-by date.

Yes, you can safely mix milk from different dates in the milk container, as long as all the milk is still within the shortest use-by date. This ensures the milk is safe to use. 

In addition to keeping an eye on the use-by dates, it’s also important to regularly clean and sanitise any containers that are reused to store and handle dairy products. This helps maintain overall hygiene.