There are two parts. First you need to extract the actual need from the client, which most likely is not what they told you. Five Whys or plain old requirements engineering is the way to go there. When you got that, then you should check conceptional distance. How far away from your existing design is the change request? Is there a way to abstract out a superset that includes the CR? And also, are there other foreseeable changes "in between" or close by in the conceptional landscape?

During the project initiation phase, it is crucial to establish robust documentation and clear agreements for effective 'Change Management'. This includes outlining a structured process for handling feature change requests and securing approval of the Scope of Work (SOW) from all stakeholders. An adept designer also anticipates the possibility of evolving client needs by incorporating buffer time into the project estimates. This proactive approach ensures flexibility and minimizes disruptions while maintaining alignment with project goals and stakeholder expectations.

Step 1 Is always listen carefully all the requirements from Client. Note it down.. Step 2 Then one by one talk on each requirement how much cost required efforts required and if any alternative and feasible solution if we suggest them and ask their inputs on that. Note. While Giving suggestions solution you should be confident on what you are talking. As developer present approach like we can create and test this solutions in lower environment and then again will connect for review. By these way, you can open up on multiple approaches and solutions.

1. Why? And from good clients.. they have good reason.. 2. Legacy code... If code is good it is easy .. And fix must be small in number of lines... 3. If it is bad code... That is time to ask account managers to set price for change. And fix must be big in deleting number of lines. 4. In any case.. we must do it...