I apologize for posting twice – nothing apparently happened the first time I clicked. Now I’m replying to both responses.
Thanks! That did the trick. So, we can select the cutaway clip, type “Q” to connect it to the Storyline, then “Command-g” to make the clip a secondary storyline. Two keystrokes. Then “Command-t” to add Cross Dissolve. It appears it is possible to stack storylines for compositing, like tracks in FCP7.
My next question is how do we change the length of the dissolve without going into Preferences? In FCP 7, double clicking the transition brings it up in the Viewer, where the duration can be lengthened, say from one to two seconds.