1) Install the Module
Go to the Odoo Apps menu and install the module.

2) Go to the invoice app:

3) Users can select multiple invoices from the list and perform invoice merging from the Actions menu.

4) Click on merge action menu.

5) Users can review selected invoices, choose whether to create a new document or merge into an existing one, and select post-merge actions like keeping, canceling, or deleting the original invoices.

6) Created a new invoice.

7) Create a new invoice with a new customer and other selected invoice move to cancel stage.

8)If the user selects 'Delete Originals', the original invoices will be deleted and a new merged invoice will be created..

9) Select 'Keep Originals', configure the required options such as merging chatter messages and allowing different partners or currencies, review the quantities, and click 'Merge' to complete the invoice merge process.