Lead wolf retirement questions?

Hello! My lead wolf is nearing the age of retirement and I was unsure of how naming a heir would work with what I want to do.

I plan on replacing him with his kid, though she's 4yo now. I wasn't sure if I needed an heir that was under a certain age or if there was a limit to how old one could be.

I haven't replaced my lead yet, but from what I've seen when your lead dies you'll be prompted to choose a new one from your pack or create a new one (the way you created your first). There are no restrictions to the wolf you pick, they can be any age.

Thank you so much!