An alternative way to copy the transitions associated with a particular stratum into an existing scenario is the following:
1. Define the new stratum in the Project Properties | Strata
2. In the Transition Pathway Diagrams, go to the stratum tab that you want to copy from in the Transition Pathways and select everything with your mouse (i.e., all state classes and transitions) by holding done the left button and drawing a rectangle around all state class boxes.
3. Right Click, Copy
4. Right click, paste into the tab for the new stratum.
5. To copy in initial conditions and other properties you will need to export to excel and copy the records for the new stratum.
This method actually also works between projects and libraries as long as the definitions in the destination project are identical to the definitions in the source project. This may actually be an easier approach than the one posted above.