Milter-greylist

We plan to deploy milter-greylist for our ISP customers.

Right now we have web interface which lets individual users enable/disable 
greylisting for their account. We use milter-greylist with -T and specify 
individual users in greylist.conf who want greylisting.

Individual users will want to whitelist individual senders from 
greylisting. Their individual whitelist selections _must not_ affect other 
users. E.g. a whitelist must be specific to that user. A user's whitelist 
for *@*.uu.net _must not_ affect any other users.

I can't see any way to do this with existing milter-greylist. Am I wrong?

-Dan