Can someone help me with this facebook problem.?

[Vikram]

I'll answer you in a perfect and easy way but rate me full,

Eg 1; A and B are friends on facebook, they keep chatting for months and months on facebook.

Now A unfriended B,

Now 'B' Dosn't know 'A' unfriended him, B tries to find 'A' in his friends list,

B can't find 'A' but can see his name in his messages,

Now if B clicks on A s name he can see his profile as ADD friend.

Now if B clicks on add again then if A accepts his request then everytime when both are online they can see each other as online, or theyll not appear online to each other when both are online.