"WAAC and WMMSC are affiliates of the Debtor". WAAC and WMMSC were the Securitization issuer for WMB. Yes, WAAC and WMMSC are 510(b). Therefore all Securitizations by WAAC and WMMSC are in 510(b) and paid into Tranche 5, 510(b). The Securitizations themselves will satisfy MARTA and TMF claims with their CERTs owned.
What doesn't belong to other institutions like MARTA and TMF, and that was invested in by WMI subs like WMIIC go to Tranche 6 class specific participation for distributions. Same for the payment for "WMB and it's assets".
WMI is a creditor to WMB. With the purchase of the bank WMB by the FDIC, JPM takes responsibility for all Class 17 WMB Notes.