You can group your contacts for things they may have in common eg members of a particular Section.  This will allow you to send an identical invoice to all members of a contact Group with minimal work (please note that you can only invoice a contact group in classic invoicing).

Create and edit contact groups (xero.com) and Invoice a group of customers (xero.com)

If you have queries please email financehelpdesk@scoutsqld.com.au