novation
From Longman Business Dictionarynovationno‧va‧tion /nəʊˈveɪʃənnoʊ-/ noun [countable, uncountable]LAW when there is a change of one or more of the people or organizations that have agreed to a contract, with the permission of the other people or organizations involvedThe suit is based on the contract-law principle of novation: duties and obligations of a contract can’t be transferred without the consent of both parties.