I have made alliance with almost every faction atleast once. A large portion still remain an ally, or neutral with trade rights. Since the Brutii and Scipii are my allies, they can't expand if I ally with whoever they are fighting against.
The Brutii is exclusively limited to Southern Italy and the west coast of Greece. The Scipii have only the one city in Italy and the three cities on Sicily.
So basically, this is the most opportune moment for me to act... despite Briton having just stabbed me in the back. (I know from experience that they're a royal pain in the ass. I conquered one of their cities four times. Three of those four, I slaughtered the populous and they still rebelled. I think I'll just go in, slaughter them all and leave it to the rebels.)
Should I move south through Italy, taking Rome first, then down to the southern tip and into Greece to attack the Brutii with Macedon's help? Or keep a garrison in my Italian cities and attack the other Romans from the outside in (easiest method)?
And finally, is there a way to have the Brutii and Scipii help me attack Rome, then ally with one of them to kill the other?