Debtors filed an adversary proceeding seeking a declaratory judgment that any claims asserted by defendant in debtors' bankruptcy had been settled by contract, in addition to other relief. Defendant filed a motion to dismiss the adversary complaint, asserting the court lacked jurisdiction under N. Pipeline Constr. Co. v. Marathon Pipe Line Co., 458 U.S. 50 (1982). The court held that the district court's interim rule after Marathon, which had been validated by the Tenth Circuit, gave the court jurisdiction over "bankruptcy proceedings," and that debtors' adversary, which dealt with their eligibility to be chapter 13 debtors, was just such a matter. Additionally, the court noted that it continued to have jurisdiction pursuant to 28 U.S.C. § 157, as the adversary was a "core matter."