Pause before promising
Acknowledge the idea and compare it with the signed scope before estimating. Do not let urgency turn a useful request into an accidental promise.
State whether the request replaces an existing deliverable or adds work. A trade can sometimes preserve the schedule and fee.
Price the decision
Describe the added output, assumptions, fee, schedule effect, and approval required. Keep the change small enough to understand without reopening the entire agreement.
If the request is still unclear, estimate a short discovery step instead of guessing at the full change.
Update the working record
Get approval in writing before beginning. Add the approved change to the project record and update milestones that depend on it.
A consistent process makes change feel professional, not confrontational.