Question

A Torah scroll belonged to my ancestors.
The Nazis occupied the area and it was lost in the war and in the camps.
At some point, some descendant of the family received it from some community somewhere in the world that holds old Torah scrolls.
There were several clear identifying marks.
 
Now the question is:
Is this a case like “saved from the lion and from the bear, from a flood of a river,” etc., and does it belong to the descendant who found it or to all the survivors?
If the community gave it to him, does it belong to that descendant or to all the survivors?
Did the Nazis acquire it under the law that conquest effects acquisition, like “Ammon and Moab were purified through Sihon”? Whoever stole it from them would seemingly have acquired ownerless property? Or perhaps, since nowadays international law accepts that civilian looting is forbidden, and that is part of the understanding under which wars are fought, maybe today conquest no longer effects acquisition? The practical difference is whether it was expropriated from the murdered grandfather and now belongs to whoever has it in his possession, or whether it belongs to all the descendants?