One BU and multiple Inventory organizations located in different cities

Summary:

In one Government organization with a head office and multiple branches, located in different cities, we implement One Requisition BU and one Inventory org for each branch, we have three issues:

1/How  grantee that requesters in specific location/branch can  query only their requisitions ,and one specific requester  can query all requisitions in his/her location/branch, also a general requester in head office could query about all requisitions over all locations.

2/ Also, we need same scenario exactly for POs.

3/ in the AP invoices for specific location/branch we need to prevent matching POs for other locations.

Any advice how to implement this security model ,or implementing business model it self?