Which lines are you thinking of, specifically? Aside from "the Force is strong in my family"? There's no evidence to suggest what you're saying about the Jedi picking and choosing. And if there were known Force bloodlines, they'd be part of the Jedi Order, not on some distant planet a Jedi would have to travel to in order to pick up the latest Force Baby. And as for Rebels, Caleb chose the name Kanan Jarrus when he went into hiding during the Purge. It's nothing to do with the Jedi giving anyone new names.