Welcome, Torberry, and I hope that some of the real experts on this forum will be able to help you and that you'll get some of the answers that will...
Acording to 'The Captive Luftwaffe' (Kenneth West), there were two! The first was Do 217M-1 (c/n 56158), AM 107, which is said to have been earmarked...
Sadly it didn't happen last year and if it's going to happen this year, so far there's no advance publicity for it and nothing on the museum website....