In the Idea Workspace >in the Overview, Value, Risk, Agreement, or Plan tab spaces:

Step 1: Select Edit button next to the Idea information on the top-right corner of the page.

Step 2: Select the main tab called Team.

Step 3: Select the Add + button in the far-right corner of the Team Members section.

Step 4: Type in the email account or name of the person you want to add as a Team Member

Step 5 (optional): Select the send invitation+ button to add other Team Members.

Step 6: Select the done button.

How to assign/change/remove your Idea Team Members?