Is there an API/function to get the payment method for a supplier site?

I am building a report and need to determine the payment method for a supplier site, including for cases where there is no default is checked at site level.

For example, for a supplier Sup1 with Site1 and Site2:

Sup1 has Check as the default, Site1 has nothing checked and Site2 has EFT is checked.  I would like the listing as below

Sup1, Site1, Check

Sup1, Site2, EFT

I tried to build it using tables iby_external_payees_all and iby_ext_party_pmt_mthds but couldn't come up with a simple query.

I found support note that suggests the below query, but it doesn't return a site if there no default checked