I looked at the rugged detonators Mr. Cuervo placed on the table and if things went as they should, there would've been three less seats surrounding the round table. Truth be told, every head in Mr. Cuervo's organization seemed like they were friends for a long time but if we're talking about their deep history with each other, they have enough reason to slit each other's throats given the chance.
From the top of my head, I know that Mauro and Sal knew of the plan—even though I had no idea they were the heads of their families—but they too had to have a person or two to confide in: Quinn and Elsa respectively, as far as I know.
At first, I actually didn't care who the fuck was gonna survive but Mr. Cuervo actually made the right decision of choosing allies if he had to let go of a few to move forward. If I was in his shoes, I would've done the same thing and to have a political/genuine wedding to merge the other two families that would be left was a great choice.