How do Amendment Quotes work in CPQ?

An Amendment Quote is created to modify an active contract mid-term — adding, removing, or changing subscription quantities. Key characteristics:

1. Quote Type: Set to "Amendment" on the SBQQ__Quote__c record.
2. The amendment quote is triggered from the Contract record via the "Amend" button, which creates a new Opportunity and Quote. CPQ pre-populates the quote lines with the current contracted subscriptions.
3. Delta Quantity: The quantity on an amendment line represents the change (positive for additions, negative for removals) rather than the total quantity. CPQ calculates the net new ARR/MRR.
4. Delta MRR: The monthly recurring revenue change from the amendment — visible on the quote line and useful for reporting.
5. Co-termination: The amendment subscription term runs from the amendment effective date to the contract end date, ensuring all subscriptions renew together. Pro-ration is applied automatically based on the remaining term.
6. Contracted pricing from the original contract is preserved on amendment lines unless explicitly overridden.