If you want to populate cities a far cheaper, easier and quicker way just use the add_population cheat on a city with a large population, and move some to the settlements with low population. Roleplay it however you wish.

For example:

add_population Roma -4000
add_population Arretium 2000
add_population Taras 500
add_population Capua 300
add_population Rhegium 200