Unwed and baby last name?

Idk how to tell my ex I want our baby to have my last name. I have a child from a previous relationship who shares my last name. I would like my kids to have the same last name.

We’ve never been married, & it makes sense to me. I considered hyphenating but down the road once the baby is older I think it’ll just be such a hassle bc we both have long last names.

My ex is a 3rd, he wants to pass down his name if it’s a boy.. so I feel bad bursting his bubble.

Pros and cons?