Awkward Staircase, looking for some advise or help to fix

Hello people.

I have a project where a client has a basic Revit model staircase that they have provided me with. They have then asked to use the same footprint and the same set up for the steps but to create a much more organic and sweeping stairs. I have done this in the past in residential houses over 1 flight of stairs. But with this being on the large scale, I have come into a slight problem. As you can see the general form and shape of the outer and inner frame is in place. But where the underside of the stairs wants to have a smooth sweeping finish…it’s not working. I’m no pro on cuviloft or soup bubble, but sadly the results from these aren’t great. I appreciate any advise on what I could try to do, and if it means re modelling the inner and outter that’s not a problem. Happy to provide the model if anyone fancies a challenge. See attached some screen shots of original and new model.

Thank you