Both Connie and Vito's wife have complained to Vito about Carlo's abuse of Connie and urged some sort of intervention. Vito has refused to do this, mostly because he believes in staying out of marital disputes as well as thinking every man is a king in his own home. Even knowing that his only daughter is getting the stuffing beaten out of her on a regular basis Vito refuses to use the considerable resources at his disposal to "convince" Carlo to stop. So staying out of domestic disputes is apparently a pretty important goal for Vito.

Vito ordered Sonny not to intervene. Vito was apparently pretty po'd that Sonny did intervene.

"But the Tattaglia Family had not streamlined itself for the war, [the news about Sonny’s appearance and assault of Carlo]still had to go all the way through the insulation layers before [it] finally got to the caporegime who contacted the Tattaglia chief. By that time Sonny Corleone was safely back in the mall, in his father’s house, in Long Beach , about to face his father’s wrath.”

Angry about his public humiliation, Carlo either approaches or is approached by the Barzinis--goodbye Sonny.

But what if Carlo had gone to the mall to complain in person to Vito? How would Vito have handled it? Was there a way Vito could have finessed this situation that would have (1) Given Carlo some sense of justice (2) Stopped the beatings (3) Prevented Sonny from reacting violently again (4) Allowed Vito to maintain his non-interference policy.