What kind of pellets are you feeding them? What kind of fruits?
FYI - one good fruit for RES's are fresh blueberries, which are high in antioxidants, especially Vitaman E, which helps shedding. It takes time to shed though so don't just expect that if you give them a blueberry one day, that they will shed the next day.

I like blueberries for Sheba because I don't have to cut/peel anything. I just wash and toss in the tank. Easy.
Otherwise, I see a lot of growth on them which is a good sign & their shells look clear & healthy with good color. I can see in some of the pictures that some of the scutes are starting to lift around the edges.
Don't worry about *when* the scutes will shed....they just shed on their own eventually.
How long have you had these turtles?