WEp1 - Existing tenant space conditions

I am working on a CS existing building renovation project. There are existing toilet rooms on the floors that are "tenant controlled". In the tenant controlled bathrooms do I need to use the flow rates for the existing fixtures or should I use the default rates per LEED 2009? I know I can use lower fixture rates in tenant spaces if the tenant agreement is mandatory (and I have a list of low-flow fixture standards they would have to meet); however, I am not sure how to handle the existing bathrooms in the tenant spaces that are out of the owners control (at this point). Any help would be appreciated...Thanks