by slIchCltange, lind an appropriate Chllnge Order sballbe' issued before conmlenCel1lent ofthe substitute Subcontractor's Work. However,no increase in tbe Contract Sum or Contract Time shall be allowed for such changeunlt;lsstheContractorhas acted promptly and responsively in sulllnitting nalJ1es ~ req\iired. '
§ 5.2.4 TIle Contractor shall not substitlite a Subcontrl\ctor, p¢rson or entity previously s¢lecied ifthe Owner or Architect makes reasonable objection to such substitution.
§ 5.3 SUBCONTRACTUAL RELATIONS ay appropriate agreement, written ,,,here. legaUy required for validity, the Contractor shall require each Subcoiltractor, to the extent ofthe Work to be performed by the Subcontractor, tQ ~b9Ulld to tltl;\ Contract!))' by terms oftbe Contract Docullieuts, and to assume toward the c;oiltractqr all the 9bligatioll~ and rCspollsib.iIitit