Hi,
Unlike definitions (which can be shared between business contexts), objects created in the Designer workspace in CI Studio (Campaigns, Scenarios, and Treatments) cannot be shared between business contexts.
However using SAS Management Console, you can export the treatment from one business context and import it into another business context, When you do this you are essentially creating a second copy of the Treatment (in metadata you would see 2 objects with the same name in the 2 different business context folders). The second copy of the Treatment will have the same Treatment Code (e.g. TRT436) in both treatments, but if you are using Treatment Tracking Codes (which is based upon the Treatment_SK), each treatment would have a different tracking code.
Regards
James