What is the term for substituting one contract for another?

The correct term for substituting one contract for another is "novation of contracts." Novation involves the replacement of one of the original parties in a contract with the consent of all parties involved. This means that a new contract is created that extinguishes the original obligation, effectively substituting the existing agreement with a new one.

In the context of real estate, novation can occur when a buyer is replaced by another buyer, or when a lease agreement is transferred to a new tenant. It is critical to understand that under novation, all parties must agree to the new contract, and the original party is released from their obligations under the initial contract.

The other terms listed, while related to contracts, do not accurately capture the process of substituting one contract for another. Assignment refers to transferring benefits or rights under a contract without releasing the original party from obligations. Modification involves changing the terms of an existing contract rather than creating a new one, and termination simply means ending a contract without substitution or transfer.