Yes, it is possible to group invoices by warehouse in Odoo. You can do this by creating a new group in the invoice form view and setting the group by attribute to the "Warehouse" field. This will group the lines in the invoice according to the warehouse they are associated with.

Here are the steps to create a group by warehouse in an invoice form view:

1. Go to the Settings menu and select the "Technical" sub-menu.

2. In the "Technical" menu, select the "Reports" option.

3. Click on the "Invoice Forms" option to open the invoice form view.

4. In the invoice form view, click on the "Edit" button.

5. Click on the "Add an item" button and select the "Group" option from the dropdown menu.

6. Set the "Group By" attribute of the new group to "Warehouse".

7. Save the changes to the invoice form view.

After making these changes, the lines in the invoice will be grouped according to the warehouse they are associated with. You can also customize the group header to display the warehouse name or other relevant information.

Just Place the Warehouse field on the Invoice while creating the Invoice from the any other document then it will be available the the group by.