Don't confuse the PMBOK process groups with project lifecycle phases. Yes, their names sound like phases, but they are not as the processes within those process groups are performed iteratively over the full life of a project.
What you can do is look at the phases of an E-Discovery project and the nature of the project management activities performed within each of those phases and map those back to the five process groups.
Agree with Kiron. The process groups are a guideline only for the typical nature of projects. It's the 47 processes in PMBOK 5 that you choose within your own project lifecycle that matters most. If this isn't for the PMP exam, and it is related to a work project, perhaps look at PMBOK 6 and the 49 processes. Saving Changes...
