tagging/sharing - show people within the project first

When a user shares a document, they need to click on the people tab and enter the names of the people they need to share it with. Our users work with a lot of people in different projects so they requested that when they need to share/tag people in the project/documents area, they'd see the project users identified first as the available users so it's easier for them to tag those involved than having to recall who's included in the project.