I had a very troubled child hood and i used to pick at my skin till it bled. what my adoptive mom did was give me bandaides where i picked. If i took them off shed go a next size bigger and so on and so on. I stopped after awhile cause i didnt want huge bandaided all over my body. maybe try that.
I am thinking maybe you could put a dressing over it , not a band Aid as that will keep it moist and it will take longer to heal, maybe a light dressing and it will stop her scartching as much,and how about a 'reward for each one she allows to heal, make it a game and a project for her , take the sting " so to speak ,out of it!
Have you tried some medicine to relieve the itching. Some people have an allergic reaction to bug bites which causes the itch to itch more. Also, there may be allergies she is having carried in the air which causes extreme itching. I am a itching person too. I know that I itch more and swell more from bug bites than other people. Talk to your doctor about this. I think she either has allergic reactions or maybe even an overactive immune system.