Ive been testing and looking for this issue. When you saw the damage was it right after the drone exploded?
I.E. The damage was transferred at the death of the drone, or was damage shown when the drone kept flying?
HiTech
First, I only saw damage 'transferred from lead to drone(s). When I attacked a He 111 drone first, it went down with any visibly damage to the other ships. After that I removed a wing from the lead (which started to plunge down). After that the remaining drone (now lead) had suddenly oil leak on the same wing. I
think that phoney damage only came into existance after the Heinkel pilot bailed from the falling lead, but I can't tell for 100% sure.
In the other cases the lead bombers died to quick to tell exactly the point at which the damage was transferred, and I usually don't have a vis on the bombers when egressing (I do very fast high angle slashing attacks and usually shoot late).
I hope I can do another test this evening (US afternoon)