I have noticed that the claim form ONLY appears if the replay says you personally shot down the airplane. Of course, you only find this out later, because the claim form comes up before you can watch the replay. But apparently there's something in the game that decides that you have a valid claim, and therefore brings up the claim form, and that this same thing is what makes the replay say you actually shot down the enemy in question.
This seems to be the case even if 1) no other airborne friendlies even fired at the enemy, 2) you shot him up badly, 3) there's no message in the replay that Archie hit him, and 4) he ended up crashing during your fight with him.
The other day I fought 3 Albatri alone, hit at least 2 of them badly, and 2 ended up crashing during the fight. But I didn't see either go down, I just noticed their burning wrecks later during the same fight. I know for sure I hit 1 of those that crashed, because I saw the other (and most hit) enemy fly away. Archie was shooting at them all. However, the replay showed no Archie hits, so the 2 dead ones went down either due to the damage I gave them, or from stalling while maneuvering with me. Either way, I feel responsible for their deaths. However, the claim for didn't come up and the replay just said they'd crashed, not that I'd shot them down.
Maybe you have to see the enemy crash or at least catch fire to be able to file a claim? I don't know.
The problem here is that you have no opportunity to lie at all. I would have filed a probable on both those that went down AND the damaged one that flew away, because he looked unable to get much further. But I didn't get the chance.
At other times, I've known I got some guys and think I'm justified in claiming others. IOW, 1 definitely down in flames, and another last seen going down after bad hits, and then a few seconds later you note a burning wreck below in the area where you last saw that guy headed. So when the claim form comes up, I use 2 lines, 1 for the flamer and 1 for the guy I assume I shot down. However, I get the message that my claim will automatically be rejected until I remove the non-flamer.
The result of all this is that after a battle, there are often 2 or 3 dead enemies for which nobody can file a claim. Not you, nor your AI wingmen. But somebody should get credit for them
. Of course, I'm spoiled from the "manuever kills" handed out in Aces High....