Steps to Merge Invoices
In the left sidebar, click the billing icon to open the Billing module.
Click on the "Invoices" tab.
Check the boxes next to the invoices you want to merge. Make sure all selected invoices belong to the same client.
Click the "Merge" button at the top of the list.
Confirm the merge action.
Note: Once merged, a consolidated invoice is created. Review all services and balances carefully before confirming the merge.