Is there a way to create a parent page from a regular page?

Thanks. As it turns out, I could drag to the parent-page area if I selected both pages in the spread.

Now I need to make one that is a mirror-image: This one has a big fold-out page on the right; now I need one with the fold-out on the left. I thought I’d say “duplicate spread” (on the child pages, not the parent spread) and then swap the pages around, but “duplicate spread” doesn’t appear to work correctly. It adds pages to the document as displayed in the editing pane, but they are missing from the Pages pane.

“Duplicate spread at end of document” produces the same behavior.

Screen grab attached.

Update: There are a couple of bugs in play here, potentially. Or a bug and a bad design choice. I discovered that there were three copies of the wide-layout pages in the document itself, but only one spread showed in the Pages pane. After deleting the two undisclosed ones, I… don’t remember exactly what I did.

But at some point I discovered that InDesign decided to put further copies of the wide spread into an “alternate layouts” column in the Pages pane without asking. Yes… because viewing your document’s pages out of order is the logical default, Adobe.

Anyone, I restored the logical order of the Pages pane by undoing the view option I never selected, and seem to have accomplished what I wanted.