May be, you shouldn't do. You will be 'bombarded' with new family members after the conquest of one or two towns and will have no real use for puppet rulers and mercenary generals - if not for role playing reasons.

I am now around 240 BC and have eleven family members sitting idle in Rome, of whom some are much better than most of the puppets I had installed everywhere. For game play purposes I wouldn't install any further puppets; for role playing reasons, I will at least limited the puppets to important Greek cities. Massalia and Syrakusae will be the last in the West, and in the East I will limit them very much, too.