Planning security question on Write access to specific intersection

Greetings,

We are on 11.1.2.2..  We have a Planning database where each user is assigned WRITE access based on group tagged to members, as such below.  All access is granted via groups only.

• User 1 has write access to groups for France,     Dept20, Unit30, and Acct100, Acct200
• User 2 has write access to groups for Germany, Dept21, Unit31, and Acct200, Acct300
• User 3 has write access to groups for Spain,      Dept22, Unit32, and Acct300, Acct400

The security assignment was straightforward, until recently where

• User 3 now needs write access to France, Dept20, Unit30, and Acct100, Acct200. 

The issue now is that user 3 may also have write access to an invalid combination of the intersection, ie User 3 may end up by updating Spain using the France intersection: Dept20 and Unit 30, and Acct100 and Acct200.