If Michael was killed on “his return from Sicily” Corleones annihilated

Originally Posted by Evita
Wouldn't Vito's undertaking that he will not be the one to break the peace pact, binding on all the Corleone family
Originally Posted by Turnbull
No. Michael wasn't at the Commission meeting, when Vito swore that ..."I will not be the first to break the peace we have made here today." Vito died without breaking the peace. Afterward, Michael figured, correctly, that Barzini was going to break the peace by killing him.

Don't know Turnbull aside to the peace pact for the drugs, Philip Tattaglia and Vito Corleone agreed to forgo any individual vendetta which I reckon would be binding on their respective Families too

If another Corleone or another Tattaglia attempt vengeance, without any provocation, I reckon it would be breaking that agreement and their word

I reckon "I is on behalf of the Family otherwise ridiculous "moral" distinction by circumstance: