Different Entity Security in Different Cubes and/or Scenarios

Thanks for your feedback - do you mean data cell access security?  I thought that this kicked in AFTER entity and scenario security, and was generally used to refine security that has been privileged via other security groups.  In my example, I think that I need to provide R/W security access to the 6 entities that I mention to my user that needs 3 entities in the finance cube and 3 other entities in tax cube.  Would I then remove the 3 finance entities as part of slice security in the tax cube, and similarly remove the 3 tax entities in slice security in finance?  This might be very voluminous as I have over 100 entities, and over 50 users - Is Data Access security supposed to be used with this volume?