How are these custom email templates used? Is it only when sending an invoice where you have the option to select which email is to send?
In my ongoing efforts to inform a subset of clients who pre-pay I think my only option at this point is to us the $client_balance and it looks like the only place this is usable is in an email (request put in for invoice usage as suggested). So I could add this string to the payment email but it only applies to about half of our clients. Is there a way to have different payment emails or use the above templates for only specific payments?