Unable to hide alternate hierarchies in account dimension with shared members in PBCS application

Hi,

As part of a business requirement, I am trying to hide some of the alternate hierarchies in account dimension from user view. I am giving (None) access to the parent member and it's descendants in the alternate hierarchy but after applying this, I am observing that all the child members start to come as a flat list.

Please could you help me understand if it's possible to hide these hierarchies. If yes, please guide me how we can achieve this.