PHP: Passing POST data to an iFrame within same file [closed]

Please I need help to unblock this problem.

So I have a large form with multiple steps, within the same file. The fourth step of this form has an iFrame that I intend to use to generate a pdf invoice.

The problem here is I am unable to to pass POST data to this invoice (in the iFrame) that requires the organization name, address, etc.

Note: I implemented JQuery/Ajax to preventDefault and parse POST to a different action php page.

Thanks

Pass POST data to iFrame within same page.