For all gateways except Authorize.NET, it is possible to convert a one-time credit card into a regular credit card, which is added to a business partner.
To do this, access the credit card form of a business partner, here you will find the "Convert one-time card" button.
When you open the conversion screen, you will see a list of documents with one-time credit cards available to convert. You then have the option of selecting the card you want to convert, and confirming the choice by clicking OK. iPayment will then try to convert the one-time credit card into a business partner card and attach it to the customer.
Please note: This feature is not available for Authorize.NET.