Dont know if this was addressed or not, in the beginning of g1, when tom is talking to vito during the wedding scenes about carlo, vito says to never discuss family business in front of him. But near the end of g1 during the big mmeeting in vitos office about the move to vegas, carlo is sitting in. Why is this, this is what i would consider a high level meeting and carlo could / would go running right to barzini and blab.