How do I mark an invoice partially paid in Microsoft Access Desktop Services?

[kashrus]

I am using Microsoft Access Services template for billing. A customer gave partial payment for an invoice. (For example he owed $700 and paid $200, now he owes $500.) The problem is that if I click "mark paid" it marks the invoice as fully paid which is not the case. I also can't change the amount on the invoice to reflect the new amount owed because once you submit an invoice you cannot change it. I am looking for a way to either A) change the invoice, or B) keep the original invoice but add a line to show that it was partially paid, and when I print the invoice it should show the new amount on it. Thank you.

[Perceptus]

I developed a custom system to handle this process. I recommend moving the unfinished invoice portions to a new invoice. and invoicing the previous for the completed. I have no knowledge of the template you speak of.

[orange]

It is difficult to answer your question since readers have no details of your database structure nor your business rules.
Here is a generic data model re Customers and Payments that may be of some help.

Quite often a Customer has an Account. When Customer makes a Purchase an Invoice is generated. When a Customer makes payment the Payment is associated with his/her Account. You do not necessarily associate a Payment with an Invoice. You could identify Payments and calculate current Account Balance. But Customers do not always pay the invoiced amount in one payment. Does your design allow for partial payments? Should it?
I don't advise you to adjust invoices. You could create an invoice or a request for payment based on the current balance.

Hope it's helpful.
Good luck with your project.