Different payment methods in one form

I understand that you're aware that you can only have 1 payment method in 1 form. You can actually have 2 payment methods in 1 form.

The solution is to create another form that has a payment method on it. After that, embed that form in the main form that has a payment method as well using the Iframe embed widget.

Please refer to these 2 detailed guides:
How-to-Create-a-Basic-Multiple-Payment-form
How-to-Update-the-Multiple-Payment-Form

Hope that helps. Thank you.