Placing a Z-cut ellipsoid

Greetings, I want to place a z-cut ellipsoid which has the curvature same as the sphere where it it flush fit. This means, the ellipsoid has the radius of curvature as the sphere it is flush fit, but cut in a way that only has a small height.
While placing the ellipsoid in the sphere which is a mother volume do I use G4ThreeVector (0,0,0) or assume it only as a cap and use translation too?
I am confused whether to assume the cap as a big sphere (just there is some invisible part) or just as a cap.

See the sketch for refence.

Geant4 Version: 10.4
_Operating System:_AlmaLinux 9.4

Use G4ThreeVector(0,0,0).

The transformation in G4PVPlacement defines the position of the local coordinate system of the daughter volume in the coordinate system of the mother volume.