Problem
The current Employee list is not updated in a Shared Distribution Group
Environment
You are the owner of an email distribution group
Resolution
Sign in to Outlook (https://outlook.office.com/) on the web and select the People icon on the left side
Under Owner, find the group you wish to update
Click Members
Click "Add Members" on the right side to add
To remove, click the "X" next to the person you wish to remove.
You can also promote someone to an owner, by clicking the down area next to "Member" and changing to Owner.
Cause
Update