Keeping the bandages on the legs from sliding down has always been a challenge for many with EB.
This is how we keep them to stay up.
I cut a piece of Blue-line tubifast the length of the leg and then add 5". I then cut a slit on one side at the top that is about 5" long.
Then this is how it goes on the leg and up over the belly
We then use rolled gauze to wrap around the torso securing the flaps in place. You could also just let the flaps hang over the edge of the diaper as well.
It helps hold everything in place and helps keeps the bandages clean and can be changed through out of the day if needed.