Is it possible to use donor fat for a fat transfer procedure?

This is absolutely not safe.  Fat has antigenic properties ( properties unique to each person) and a transfer from one human to another could cause very serious and life threatening issues

It is absolutely unacceptable to use donor fat in any fat transfer. There are numerous specific proteins and other unique antigens  that are carried by each individual. If they are transferred into another person, a severe allergic reaction commences. This produces a foreign allergic reaction. It  can be extremely dangerous and even life-threatening. Hope this helps. Good luck.