What do I do to convert a page created in the old way to a page that has an "Edit with form" option?
Supplementary question that broke the camel's back and made me start this: Why do I sometimes click on a person link (e.g. a child) on a "with forms" page and get an ordinary "Create this page" page (with the new smart option of a blank page or a partly-structured page, neither of which offers "Edit with form")?
OK, the real experts must be busy. I would still like an answer to the supplementary question, but I worked out the answer to the first. See the instructions for it.
(Briefly - you copy its pagename then use the "Create new article" link near the top of the page. Old page material remains while new templates get added.)