Merge Elements: Roofs, Shells, Morphs

Use the Connect > Merge Elements command to enable priority-based intersections among any number of Roof/Shell/Morphs and other elements. (At least one of the merged elements must be a Roof, Morph or Shell.)
Note: Alternatively, you can use Roofs and Shells to trim other elements (not just merge them): this is another way to enable priority-based connections for Roofs/Shells, as well as physically trimming the target element.
3.
Use Design > Connect > Merge Elements. You are prompted to choose the element you want to merge it with.
Note: You can also select both elements before using Design > Connect > Merge Elements. In this case, you don’t have to specify any more elements, and the merge occurs in one step.