You did ask a direct question. True!
But the answer to that is not that simple. There are many ways to skin this cat, T-Splines are just one and might not even be the best, or quickest way to do so.
Generally you might want to keep that part of the geometry that interfaces with the Radial fan assuming ( sorry 😉 ) that this is currently working.
You can simply trim those part off that don't fit (Modify->split body) or delete individual surfaces in the patch environment.
Then you can either use T-Splines, or lofts either in the Model, or Patch environment.
I would go for lofts with a centerline guide rail.
Before doing all that in your current design with the timeline disabled use the align function and center all the parts on the top level origin and each individual component using the align function. That should establish somewhat of a baseline.
Then you might enable the timeline, so further design steps are recorded.