If you visit customers fortnightly but want to bill them monthly, and you use Xero or QuickBooks as your accounting software, here's the best approach.
Recommended method
Set your visits to not require invoicing - When creating or editing your fortnightly visits, uncheck the "Requires Invoicing" option
Create a recurring invoice directly in your accounting software - Set up a monthly recurring invoice in Xero or QuickBooks for the customer instead of generating invoices through SortScape
Why this works best
Your scheduling and visit tracking stays in SortScape
Your billing is managed directly in your accounting software where you have more control over recurring invoices
You avoid the complexity of trying to combine multiple fortnightly visits into monthly invoices