You can drop a rebreather into a backpack from the vest slot. But you cannot put the rebreather back in the into the vest slot from the backpack.
- Legacy ID
1.) Create a Diver in the editor
2.) Once in-game, drag the rebreather to the backpack and release
3.) Try to drag the rebreather back out of the backpack and to the vest slot
This may also work with vests like the Carrier but I have not tested it.
Just tested this and it is indeed true that you cannot drag the rebreather directly to its worn slot. However you can remove the rebreather from the backpack and place it onto the ground and afterwards drag it to its worn slot.