Currently we issue invoice / receipt numbers for sponsorship and donation payments constructed from using the Current Year and the Contacts ID. A reminder notice is sent out for Annual Sponsorships with an invoice number inserted. E.G. 20201234 A problem arises when there are 2 or more sponsorship payments from the contact during the year. The same invoice / receipt number is created. This can have implications for when contacts claim tax deductions.
So my query is does an invoice / receipt number generator exist in CiviMember. It would need to work within Scheduled Reminders as that is where our renewal notices are constructed and despatched.