Plan editors are like Project participants in that they are a collection of users who can edit and contribute to the Plan. However, editors cannot freely join Plans. Rather, the Plan owner must either add or approve users to become editors on the Plan.
There are two ways to add editors to a Plan that you own:
1. When editing the Plan hierarchy in the Plan Overview tab:
Click the people icon in the top-right corner of the screen, as shown below.
After clicking that icon, a pop-up will appear. In the typeahead field, search for the user by name and select them from the dropdown of results. Then click Save to add them as an editor to your Plan.
2. From the Editors section in the Insights tab:
On the right-hand side of the page, click the people icon within the Editors section. This will open the same pop-up as above.
In the pop-up that appears, search for and select the name of the user that you want to add as an editor on your Plan.