Healthcare POA Duties Definded

My Mothers HCPOA refuses to give Mother's other daughter and son a copy of the HCPOA signed form.

We are trying to clarify the HCPOA duties. She now is telling nursing home staff how to manage Mothers care.  These thing fall under the nurses scope of care. Ex: HCPOA is now telling staff times of visits for other members of family, insists Mother take many supplements that she sells at risk of contraindication of physician ordered meds, refuses to allow Mother to follow the bowel plan of NH but use the supplements which are causing painful movements because of bulk.  

How do we get HCPOA to listen to trained nursing staff? They have "given up"

Any help you may have will be appreciated.

Pat

My understanding is HCPOA expresses Mothers wishes when she can no long express wishes herself.