Is there a hole at the back for her back toe to stick out? This is a very good idea, it's similar to some that a guy on Etsy sells. I'm going to try and 3D print one.
Are the toes curled under, or is there a leg issue as well? Riboflavin (vitamin b 2) found in human b complex and in some chick vitamins, can be given in small amounts to help overcome some leg hatch issues.