A wiseguy is a wiseguy regardless of whether they're from a smaller-sized family. "Young guys wanting to join OC" don't have the chance to pick and choose a family. If a young guy wants to join Italian Organized Crime, he has to hope he's lucky enough to grow up around, work for, or somehow become associated with a made member of OC. It's never a case of "Hmm, thinkin' of joining OC - who should I send my application to?" If you're in the underworld, and develop an association with a wiseguy along the way, that wiseguy's crime family is where you'll most likely end up unless you're formally transferred.
Not to mention that associates only have limited control on who they report to. It's up to the wiseguy to "claim" an associate, and other wiseguys can counter-claim. Associates can be swapped between families.
And oftentimes an associate won't even know which family his "wiseguy's" from. At least that's how it was back in the day. Nowadays there's Google, but back in the day you'd have to know a wiseguy pretty well for him to look at you and say "I'm from the such-and-such borgata."