How to appear offline while on Xbox.com?

"Appear Offline Permanently" not working with MSN ID's in Yahoo Messenger.?

• I have this person added added in my yahoo with his/her (I either don't know the person's sex or don't wanna tell) Yahoo and MSN ID both under the same name, yet, when I specifically choose to appear offline only to that person, and make myself Available to the rest, the person is still able to see I'm online, and starts messaging me. I'm guessing this is because Yahoo is only making me appear offline only to his Yahoo ID, not to his Msn Id, that when I specially go into stealth settings under the person's name and chose to permanently appear offline, I would only appear offline to his Yahoo ID, not on his msn messenger. This is complicated....I may be wrong, maybe there is some other cause...but some help would be greatly appreciated.

• Answer:

  Simple explanation. This person is on of the many people with multiple IDs. If you appear on-line to the general public, they can use one ID just to see who is on-line and the other to harass you. As long as they never actually post anything with the 'phantom ID', there is now way to find out it is the same person.