The changes are made to the prime contract. They are also signed and approved by both parties. These changes are known as amendment (variation) to the contract. A contract amendment allows the parties to make a mutually agreed-upon change to an existing contract. An amendment can add to an existing contract, delete from it, or change parts of it. The original contract remains in place, only with some terms altered by way of the amendment.
Reference:
- Modify an Existing Contract with a Contract Amendment
- CIPS study guide page 26-28
LO 1, AC 1.1