Interesting thing today when I was flying in WOFF UE.

Date: April 26, 1916
Escadrille Americaine
Plane: Nieuport 10C1
Region: Alsace

I was flying with my ailier (wingman) covering a couple of Caudron G4 when two Fokker EIII appeared attacking the Caudrons. I was able to shoot down both Eindeckers and one pilot was Ernst Udet. Returning to my aerodrome and reporting both planes shot down, the WOFF EU program only gave me credit for one EIII as my wingman was with me the whole time when I downed both Bosch aircraft as a witness. My question: Since Ernst Udet survived WWI and died in WWII, does the WOFF UE software automatically reject kills of famous WWI aces that survived WWI?

Confirmations are hit-an-miss, RedOwl. I've shot down planes in friendly territory with witnesses present, had the debrief screen show them (so the program knows), and still had them rejected for lack of witnesses. Just had two today, in fact.

I use easy reporting, cause A) I'm lazy, and B) My official record is not going on my DD214. This way I can tell if I actually shot something down or was vulched by a wingman . Anyhoo, I have shot down a number of Historic Aces, even Herman Goering, lol. The way it works is you can shoot down a historic ace but you can't kill him, he will fly until he dies in real life. You will get credit for the kill if you use easy reporting.

Shoot a few more down and some will be credited. A sample of one doesn't really help
Whether you get the kill or not has nothing to do them being Aces. As BB says Aces (and Historical pilots) you shoot down will return, only to be physically out of the game when they really died.
Better descriptions on your claim form will help the odds, but no guarantee on historical/normal claims setting.