In MVMNT, you have the ability to create and send multiple invoices at once on a per customer basis
Navigate to the Accounts Receivable section under the Invoicing Tab and click the Generate Invoice button in the upper right.
That will trigger the search bar where you can search for the customer you want to create invoices for.
Once you select the Customer, a list of invoices will appear. Go through and select the ones you would like to generate an invoice for.
Any applicable docs will be able to be chosen to send along with the invoice as needed.
Once you have finished your selection, click the generate invoice button. The selected invoices will now have generated. You can then send them all to your customer at once directly through the TMS.