How to Decouple The payment Account with method of payment ?

Hi Techies,

In Journal import process using DMF I need only method of payment to be populated from file but not the Payment Account assigned to it.

Example:

My offsetAccount is fixed which comes from integration setup, but now customer is Using Cash, PIN method of payments containing payment accounts. when I try to import PayMMode as Cash or File, Automatically corresponding payment account is populating in offsetaccount. My requirement is only cash or PIN from file should be populated in method of payment field but offsetaccount should come from My integration setup. How to stop auto populate that payment account when I import Cash or PIN??

Thanks in advance.