I guess to have "Enhanced" Y service is only possible when the flight is obviosuly non full. As when other PAX aware of MPO members having things from J, they will be unhappy or feel being treated unfair. Worst if they being turn down if nonStatus PAX request for the same service , say icecream from J. So to avoid making other PAX unhappy and losing them...they will try to keep MPO memeber low profile , or just really hand them a bottle of water.
But if I really want wine from J, as I dislike Y wine which seldom are good, how should I request? Or i should be passive all the time..to avoid having embarass situation..