I'm working on a project where we are using a lot of common message types to abstract message handling logic.
Early on it became a real pain to recreate the same Multi-part message types and Ports for each Orchestration that was using these common messages.
To simplify development and maintenance of these types, I created a "Common Types" orchestration.
There is no logic in the Orchestration; it just defines commonly used schemas as Multi-Part Message Types. The associated Port Types are also defined.
Just define the type as public and reference the Common Types projects in the other Orchestration projects and you are ready to go.