Shirley: you can use silicone putty... like in this video
You can use a glue gun. Put the hot glue over another piece identical to the one that is missing. When it has cooled, peel it off and use that as a mold. Make a new piece with clay, or plaster of Paris or paper clay. Cut to fit the missing area and repaint of finish.
Can you take a picture and share?
See if this helps
Here's how to make a mold and repair
Here's another good tutorial for you: https://www.youtube.com/watch?v=_mZXvijwj8E
Use some silicone sealer to make a mold. Once dry remove and filler the mold with wood filler.
Hello. I usually carve one out of clay or wood filler and repaint
Hi Shirley, we've used our home made silicone mold to recreate missing bits on a frame. You can get the tutorial to make your own mold here - https://acraftymix.com/blog/two-ingredient-mold/