The command org-ctrl-c-minus (bound to C-c - by default) turns a region of lines into a list. You need to mark the lines you want to change first, but it works with the headlines in your example as well.

The command org-ctrl-c-minus (bound to C-c - by default) turns a region of lines into a list. You need to mark the lines you want to change first, but it works with the headlines in your example as well.

Here's a defun you might use to mark the subtree and then change it to a list:

(defun org-subtree-make-list ()
  (interactive)
  (org-mark-subtree)
  (org-ctrl-c-minus))