T-spline polysurface to a single surface

Hello, I have encountered a problem of T-Spline model I have generated. I want to generate several geodesic lines around the geometry from the base of it
, but the grasshopper component of geodesic line only support a single surface. Is there any method that I can convert the polysurface into a single surface? Or is there any method I can generate geodesic lines on the geometry? Thanks!

1.3dm (903.3 KB)
geodesic_v1_p.gh (30.9 KB)

This is a single surface generated successfully:

This is a polysurface failed: