Hi,
"PARENT GROUP" property is used to create a group structure. If you have multiple group structure within the group structure, you can use this property. This property is even used if you want to have consolidation at sub group level also. This property is refered in ownership Model
I don't see any Elimination Rule property in scope dimension
Please refer the BPC handbook: BPC440 en Col96 Consolidation
Regards,
Rahul