Is the frame plaster covered then painted !! Where it is chipped whatever the frame was covered with looks to be thick !!
If it were me,, I would just keep the entire thing as it is,,You can stabilize the corners easy enough with a little wood glue and a large syringe to inject it (get it from a vet) work from the front if possible because the glue will run to the back,,then clamp it just till barely snug,, too much will crack the surface more,,then do the opposite sides. Wipe any excess that shows on the front or back but always keep it right side up !! When that is done take it to a frame shop and get a backing and dust cover put on !! Might cost $5.00 !! Do not put glass on the front !! That was your last question from the old thread, Just keep it dusted !! Most conservators use a cleaner similar to an artificial saliva to clean the surface !! It will do no damage so if you have enough spit,, that will work to clean it !! Sounds bad but that's the best !! Just be glad the painting is small !!
