If the Mafia would have discovered Donnie Brasco on time as an FBI agent called Joseph D. Pistone, would have he been whacked? Remember the rule about killing cops and FBI agents.

What do you think?

Talking about The Bonanno Family...well it`s the Family which broke the rules most. They might have killed him...

Good question, DPN!
You're right--the usual Mafia "rule" is not to whack an honest cop. And, yes, the Bonannos were renegades.
I think they would have whacked him for the most basic reason: survival. They'd have realized that he could send them to prison for decades, but if he disappeared, he wouldn't be able to testify against them. They might have rationalized "breaking the rule" by claiming that he wasn't an "honest" cop because he posed as a wiseguy-wannabe to infiltrate their family.

I also think they killed him but they would make sure that the body was never found. In that case the FBI can do little I quess.

The 'honest cop-rule' stops when your own life or the family is in danger. It is said Gaspipe Casso the former Lucchese underboss killed an undercover agent who infiltrated his crew in the 80's. If the Bonnanos knew Brasco was an undercover-agent he would have been killed without a doubt. But I don't know in what way or by who. Because it's quite delicate to kill someone who is closely monitored.
It also depends who found out Brasco was an agent.

If only the members of the crew that Brasco infiltrated would have found out he was in the FBI, would they kill him without telling the rest of the family, fearing for there own lives (for bringing him into the family)?

When Donnie had to take out his shoes in the Chinese restaurant, he was almost discovered. Did that happen in real life?

It wasn't in the book. It was added for drama, IMO.

Thanks for the reply!

It was at a Japanese restaurant, when Donnie was ordered to take out his shoes but refused.