This technique, in requirements workshops, is also known as solution brainstorming in CRP methodology. You may use knowledge of industry best practices to push back on requirements that do not add value to the business.

As part of this negotiation, you need to provide insights into why a specific feature is not needed anymore and what the replacement is as part of the new process. Also, always seek and negotiate the necessity and impact of requirements. Knowing this allows the project delivery team to prioritize the activities.

Often, requirements come from how it works in the current system (this does not always mean how it should work). Even worse is the fact that challenges/bugs in the current system become requirements for implementation in Dynamics 365. Consultants accept these as requirements and provide custom solutions. Understand what problem you are trying to solve and get to the bottom of the issue and then brainstorm the solution using the artifacts and information that's been collected. 

Use the power of why. Why do you do this as part of your process? Often, when you get to the why, it is due to the current limitation and it can expose a requirement that is not adding value. In most cases, customization is a convenient way of providing solutions as an analyst – you are just taking the solution from the existing system and pushing your work to the developers in terms of customization.

Let's go over an example of a requirement that you should push back. We had a customer requirement to post an out-of-balance general journal entry. D365FO, Enterprise Edition doesn't support it. The reason users were asking for this to be a requirement was because the previous system had a bug that would post an out-of-balance entry in certain scenarios and then accountants had to use this feature to correct it.

Requirements are always needed and they keep coming back; hence, you should document them in your RTM and Business Requirements Document (BRD). As the list of requirements in a typical Dynamics 365 implementation is long, we recommend that you segment them rightly and have a clearly defined owner.