It is assumed that the Practice Framework architecture being customized cannot be modified directly. Thus, all changes must be stored separately from the practice framework elements being customized. If you can modify the practice configuration elements directly, you should follow the guidelines described in Roadmap: Author a New Practice Configuration.

Customizing an existing practice framework architecture involves:

• (optionally, if customizations are complex) Performing some simple sketching (Guideline: Sketching a Method) or some actual prototyping using your implementation environment (Guideline: Developing a Method Proof-of-Concept) to determine if the customizations are feasible. 
  
• Customizing the core elements. This includes structuring the customization (see Guideline: Customizing Practice Framework Core Element) and where needed, detailing the customizations (Guideline: Detailing Practice Framework Core). All core customization work must be performed within the constraints of the method framework architecture.
  
• Refining the guiding principles, including making sure the core customizations are documented and communicated (Guideline: Documenting the Practice Framework Architecture).

As you customize the practice framework architecture, it is a good idea to periodically publish the customized framework (Guideline: Publishing a Practice Framework) and review the results (Guideline: Reviewing Methods) to make sure it appears as expected (Guideline: Publishing a Practice Framework).