Change the age category dropdown to a 'Member Type' dropdown and add additional options. The membership type would work alongside the Operation Member checkbox as needed. Suggested dropdown options to include:

Junior - A member aged 15 or less. This member type would restrict the Operational Member checkbox from being selected.

Cadet / Minor (Whichever CFA's current terminology is) - A General Member that is aged 16 or 17. This membership type can have the operational member checkbox applied as required.

General - A General Member the is aged 18 or over. This membership type can have the operational member checkbox applied as required.

Prospective - For brigades that require a minimum attendance prior to progressing new memberships. Adding them as 'Prospective' would allow them to check in to events and have their attendance tracked for this to be reviewed.

Possible extras:

Brigade Life Member - This membership type can have the operational member checkbox applied as required.

CFA Life Member - This membership type can have the operational member checkbox applied as required.