Surface Splitting an Ellipsoid in Rhino

Is there any way to split an ellipsoid without making it a trimmed surface, because once it is a trimmed surface the diagrid or braced grid structure in grasshopper’s lunchbox plug in does the application to the older surface that was not splitted. Any grasshopper or Rhino trick may help

If the ellipsoid is split along an isocurve, than ShrinkTrimmedSurfaceToEdge will make it untrimmed and the base surface will correspond with what is shown on-screen. If it is split arbitrarily elsewhere, it will always be a trimmed surface - you can make it as small as possible with the shrink command above, but you cannot make it untrimmed.