Remove All or Nothing Restriction on Full Conversion Subrelations

I would like to see Conversion Subrelations have the ability to act more like 2-item and 5-item correlations such that enabling "Full Subrelations" is not an all or nothing proposition.  There are times where I would like to breakdown two eVars by one another, but don't need each fully subrelated to all eVars.  This would make my implementation cleaner and reduce the possibility of latency...