Yes. You can opt to receive all the pending payments at once from a customer by choosing a customer under Accounts >> Receive Payments. You can also opt while generating an invoice for a customer. When you create an invoice for a customer, TruckLogics will list all the unbilled amounts associated with that customer. You can choose to add the unbilled invoices right here.
You can select and add only the invoices you want to associate with that customer, the unselected invoices will remain and will be similarly listed the next time you select that particular customer to invoice.