[Resolved] Connect two points on a sphere surface with a spline arc

I’m trying to get an arc-like spline that connects two points on the surface of a sphere. The sphere represents a planet and the arc should represent a flight path for transporters.
I know how to handle splines and in/out tangents and was able to calculate the location of both spline points but I can’t get the right rotation of the spline / arc. I know two ways to achieve the correct rotation.

  1. Use local tangents and calculate the spline actor rotation
  2. Calculate the world tangents and ignore the spline actor rotation
    sadly I’m not able to achieve any of the above solutions. I know the look at rotation from point A to B but that is relative to the world up-vector, which is Z. I guess the up-vector I need is somewhat the normal of the sphere surface.

Does anyone have an idea how this can be accomplished?

Calculate the world rotation of the spline with “Make Rot from XZ” with the average normal from the start and end location as Z and the look at rotations forward vector of both points as X