An owner can invite someone to be a contributor to their desktop. The owner still owns and controls that desktop, they are just granting the priviledge to someone else of being able to add, edit, and organize content on the owner's desktop. An owner can have as many contributors as they would like.
Important - Only PRO plan owners can add a contributor to their desktop. Anyone can be granted contributor priveledges.
If the desktop is private, you need to invite the person using the email of their current middlespot account to become a follower. Once the person has accepted and become a follower, they will appear in the follower menu of the desktop.
To become a contributor, you must already be a follower of this desktop.
The owner can then tap the Contributor radio button in the followers name. It will automatically move them to become a contributor.
The desktop will now show up in the person's DESKTOPS folder under Contributing tab.
They will receive updates when changes are made on the desktop.