Tax Classification Code and Global Configuration Owner

We are in the process of moving from an upgraded 11i tax regime to a new R12 tax regimes, for several OUs (but not all). I've been creating all the Tax Rates under Global Configuration Owner, as our company structure is such that we have multiples OUs linked to multiple tax regimes, so Global Configuration Owner is the most efficient setup (allows the OUs to share tax setups). However, using Global Configuration Owner means that the automatically created Tax Classification Code lookups are not OU specific. So now all the users in all OUs are seeing the new tax rates