Who amends the legislative provisions in the body of the CPC, as distinct from exercising delegated…

Amendment of the statutory body is a legislative matter for "The competent legislature through legislation". Section 122 permits specified High Courts to alter First Schedule rules and section 128 requires those rules to be consistent with the body of the Code, so "A High Court merely by using section 122 rule-making power" cannot amend the enacted sections; Article 246 and Concurrent List entry 13 provide the constitutional legislative setting. Special procedural powers such as section 129 do not convert a court's rule into an amendment of the enacted section.