Add Collaborators to Collaborator Groups

There are two ways to add a Collaborator to Collaborator Groups: by assigning an existing contractor to an existing Collaborator Group and by inviting a new contractor to be a Collaborator on your project in Wingspan. Adding an existing Collaborator to an existing Collaborator Group requires the Collaborator ID as well as the Collaborator group ID and uses the payments/collaborator/{id}/add-group/{groupId} endpoint. Inviting a new contractor uses the /payments/collaborator endpoint and requires the contractors email address.