Mildred Davidson. Inventor. Mildred and her sister Mary invented the adjustable sanitary belt. Mildred lived with Multiple Sclerosis and used a walker or motorized scooter. Using her mobility aids led to more innovation, with Mary designing a clip on tray and basket for the walker. Her mobility decreased as years went on and Mildred spent many hours in bed. She used that time to develop a board game called “Family Treedition” about genealogy as a way to get back in touch with her extended family and inexpensive entertainment they could enjoy together. Black Disability History.