How do we give users access to calculate / consolidate using a data grid?

Data grids are great for doing multi-period, multi-year calculations/consolidations, but the Subsidiary users don't have that functionality. We've tried and tested seemingly every possible security grant and provisioning, but continue to get "Read only" as the cell status for any given period. The users are perfectly able to calc/consol in Process Control and have no trouble Promoting data using a data grid.