I'd cut the Zolcal D out now and supplement as normal (Calcium 2 - 3 times a week depending on your diet ratios). Are they clearing their bowls or leaving some? Do you give them cat biscuits? I'd be giving them about 5 biscuits each a night, and continue with the oatmeal.
Don't worry about the gliding so much, they will do it if the want/need to.
