There is so much misinformation on the net that I don't know what is fact or fiction.

In particular: The 3 capo murders

I have read in numerous places that the boss of each family has the power to eliminate anyone within his own family......It is when you want to wipe out another family's member when approval is needed.......So why is it that Rastelli had to ask the commission to kill 3 of his own? (Which I heard they denied initially but relented when they learned they planned to strike first).......Was it because of their rank? The fact that if a capo isn't safe, then 99% would lose respect for the structure?