STEPS TO REPRODUCE
1. Launch iClone 6
2. Apply two balls
3. One ball (A) attach the other (B)
4. Pick B ball, right-click and select "Convert To Terrain"
5. Pick A ball, right-click and select "Convert to Prop"

ACTUAL RESULT
Sub-props attached to a larger prop will not be hidden in the Scene manager

EXPECTED RESULT
Sub-props attached to a larger prop will hide in the Scene manager if convert it to Terrain