Scenario:
Integration between Web TimeSheet and Quick books is already completed and an invoice has already been created. Now, there are newer expenses which require to be included in the invoice which is already created. However, it is not possible to add the new expenses to an already created invoice.

Cause:
The QuickBooks integration manager does not update or append additional data to an existing invoice.
 
Workaround:
Run the integration again with the new expenses included, however doing so will create a new invoice.