With the release of R12.0.0, payment information like the Pay Alone Flag

(Exclusive_Payment_Flag) and default Payment Method are 

now stored in the table IBY_EXTERNAL_PAYEES_ALL. 

SELECT COUNT(*) 
FROM iby_external_payees_all 
WHERE exclusive_payment_flag IS NULL; 

For Supplier Payees:
SELECT IEP.ext_payee_id PAYID, NVL(IEP.exclusive_payment_flag, '*') PAYFLAG, 
APS.vendor_name VENNAME, APS.vendor_id VENID, 
NVL(APS.exclusive_payment_flag, '*') 
FROM iby_external_payees_all IEP, 
ap_suppliers APS 
WHERE APS.party_id = IEP.payee_party_id 
AND IEP.exclusive_payment_flag IS NULL ; 

For Supplier Sites:
SELECT IEP.ext_payee_id PAYID, NVL(IEP.exclusive_payment_flag, '*') PAYFLAG, 
APS.vendor_name VENNAME, APSS.vendor_id VENID, 
APSS.vendor_site_code SITENAME, APSS.vendor_site_id SITEID, 
NVL(APSS.exclusive_payment_flag, '*') 
FROM iby_external_payees_all IEP, 
ap_supplier_sites_all APSS, 
ap_suppliers APS 
WHERE APSS.vendor_site_id = IEP.supplier_site_id 
AND APSS.vendor_id = APS.vendor_id 
AND IEP.exclusive_payment_flag IS NULL