If the organization has not been registered as one of your partners, it won’t be in the list of organizations to share with. Please contact your account manager (Building Automation) or the Customer Support Center (Horticulture) to start (default) sharing with this organization.
When you contact your account manager or the Customer Support Center to add the organization for site sharing, sharing is initiated at the default level. This means that your site is shared with all permissions, and the organization appears in your list of known organizations. To limit the permissions, go into the Sites tab in Access Control to assign a role to the organization.