A team is a group of collaborators whose contributions (when merged together) create a single piece of content. Anyone that is added to a team will be asked to sign the agreement.
Ownership Agreements (Split Sheet Agreements + Premium Ownership Agreements:
Unless there is an agreement stating otherwise, such as a work for hire agreement, your collaborators can be considered as equal co-owners of your copyright, regardless of how small or large their contribution was. Using a split sheet agreement or a premium ownership agreement, you can designate any percentage of ownership to a collaborator (0%-100%).
Work for Hire Agreements:
When creating a work for hire agreement, a team should only consist of two parties - you and your contributor. Be sure to assign the person you've hired the role of "Contributor."