Yes, Qbil-Trade allows you to reuse the invoice numbers for deleted sales/miscellaneous sales invoices. Once an invoice is deleted, its invoice number is released, and you can assign it to a new invoice if necessary.
This can be done using the drop-down “Display number” while creating a new sales/miscellaneous sales invoice. The drop-down includes all the display numbers of the deleted invoices.
The drop-down menu is available when creating a new invoice only if sales/miscellaneous sales invoices have been deleted for the specific subsidiary you’re working with. This means the numbers shown in the drop-down will only include the deleted sales invoices/miscellaneous sales numbers of that subsidiary.