We've stayed in a rollin shower at the BC but it was so many years ago that I don't remember the category. I think the categories were different then anyway. But it was on the first floor, quite close to the lobby and faced the lake.
I think Linda has stayed in CR but don't know if it was MK side. But I would think if you book that view and request a rollin shower, they'll let you know immediately if there is one on that side or not.
Not trying to be nosey, but are you certain you want a rollin? I know one of your triplets has (mild?) CP but I thought he could walk. Although the rollin showers are a godsend for some like my daughter, there are downsides especially for those who are short. The toilets are raised and when she was small, that was a challenge. Even at 5", it's still hard. There are grab bars of course.
Good luck and happy planning.