Short of the limits don already has in place or tracking orders like you said whiskey Im not sure what else can be done.
Tracking the orders may be easier said than done. I have NO idea how many orders a day don does but just by watching his posts on what order hes on tells me its a pretty big number.
Keeping track of how much of one flavor each person is ordering & how often was what I was taking about Ruppy, that would help see who is being unreasonable...