Baby boy becoming a junior without the parents being married

Kelsi • Under every pretty face is something complicated ✨💚
I need help. I am 5 1/2 months pregnant and I'm having a boy. Me and my boyfriend were thinking of names. Like the baby boy being a junior and taking my boyfriends full name. Can the baby be a junior even though we aren't married. I've heard from numerous people thank you can then you can't. Does anybody know for sure?