to changes in circumstances of the debtor substantially affecting (favorably or unfavorably) the ability of the debtor to make payments under the plan, as determined by reference to the ability-to-pay test set forth in § 1325. Oversight Hearings on Personal Bankruptcy Before the Subcommittee on Monopolies and Commercial Law of the House Committee on the Judiciary, 97th Cong., 1st Sess. 181, 215-16, 221 (1981-82). While the legislative history indicates that a post-confirmation modification should be ordered pursuant to § 1329(a) upon a showing of changed circumstances which affect a debtor’s ability to pay, the case law suggests that the doctrine of res judicata limits the scope of appropriate post-confirmation modifications. In re Moseley, 74 B.R. 791, 799-800 (Bankr.C.D. Cal.1987) (<HOLDING>). In Anaheim Savings & Loan Association v.
holding that provision in chapter 13 plan discharging postpetition interest on a student loan is binding on creditor under theory of res judicata where objection was not raised prior to plan confirmation and confirmation order was not appealed holding that an order confirming a chapter 13 plan is res judicata as to all justiciable issues which were or could have been decided at the confirmation hearing holding that creditor with notice of bankruptcy could have objected to confirmation of chapter 13 plan in order contest treatment of claim holding that a bankruptcy courts order confirming a plan of reorganization constitutes a final judgment with res judicata effect binding the parties by its terms holding that res judicata precludes relitigation of issue that was or could have been decided in enforcement order that was not appealed