Keep the child's record distinct from the adult's
Create a record for each person so the club can correctly track membership type, status and history. Associate the junior with a household and identify the adult who is the approved primary contact or payer. Do not copy the adult's email into a child's email field to satisfy a form.
Member Link's household model has separate member records and household relationships. The portal can present authorised household members to a guardian account, with access controlled through household grants/capabilities. A relationship label by itself should not be treated as proof of consent or authority.