Combine not-full boxes

I would like to be able to combine the contents of two or more boxes with the same item type until a box is filled to it’s limit.

I have multiple boxes on the shelves with less then full capacity. For example, a box of 1 cheap gift and a box of 20 cheap gifts.
My suggestion is being able to combine those boxes into one of 21 cheap gifts. If the combination is more then the limit of the type in one box, then fill the first box to its max and leave the rest in the second box.

This could be done either manually in the storage interface or at the end of the day by the last staff working.

It will save space and is actually logical to do so either, right? Just drag n drop the items onto eachother to stack m. I tried it but couldn’t figure it out, so I guess this isn’t a feature yet.