A client that you have developed a close relationship with has asked you for additional services that are outside of the scope of the project. You don't want to say no because it might damage the relationship. But you don't want to say yes and now run the risk of derailing your project. Your sponsor explains that while you can't go out of scope, you do have the ability to continue the project with a new contract for the additional services.

What type of contract would be best based on the relationship and the situation?

what metrics are needed?