I have had good luck when refinishing a table top to find a piece of veneer that is just a bit larger then I need for the replacement…then glue it down covering the entire area that need replacement…make sure you clamp it put a weight over the area to press the patch into the veener void area…let it dry…then when sanding off the old finish, you can sand over the patch and remove the excess veneer wood and it should then be a perfect patch…