Boss Quest Magic Find Bug Question

[hai]

So if if i have andy,meph,diablo, or baal as an open quest and join a game where it cant be done, I can kill them and reap their MF bonus?

is there any evidence of this btw?

[Poppis]

Andy can be bugged so even if you do complete the quest, you still get quest drop from her.

For all other bosses, you need
1. A character that has not done the quest(quest6 in most acts, except act4, where its quest3).
2. You join a game that has been created by a character that has completed the quest.
3. You go kill the boss and he makes a quest drop.