It is not possible to split invoices as of the moment but as an alternative, you may add another item on the invoice. In order to
do that you will need to click Edit, add another item plus amount under Items field.

We do not have a functionality that will combine all invoices. As an alternative, you can create custom invoice that will reflect
the total amount of all the combined invoices.

You can follow the steps from here on how to create a custom