The first thing that the consultant should do to assess the situation is to document solution requirements from the groups involved. This will help the consultant understand the current state, pain points, goals, and needs of each group that uses or will use Salesforce, and how they relate to each other. This will also help the consultant determine whether EDA is a suitable solution for all groups, or whether some customization or integration is needed. Submitting a Salesforce Support case to merge orgs, installing EDA into one of the production environments, and creating a new Salesforce org using EDA as the foundation are not good first steps, because they do not involve gathering requirements from the stakeholders, and they may cause data loss or disruption. Reference:

https://trailhead.salesforce.com/en/content/learn/modules/education-cloud-basics/education-cloud-basics-discovery

https://powerofus.force.com/s/article/EDA-Migrate