Let's say I have my own account on my friends, Let's call it A. Then I change the username to B and again a month later to C. Will it still be on my friends list if I only had it added as A? Will people know that it is A?
This is the completely wrong section but yes, it will remain on the friendslist, and if you hover over the little icon to the left of a players name in your friendslist it will tell you the previous name the account had.