I suggest that searching for a member id/user name/feedback profile using a name
that has been merged into another ought to display the profile the old profile
has been merged into.
You can see http://www.bricklink.com/memberLog.asp?chgUsername=TFB.sell&h=Y that
this user has three profiles merged in, but using the top-of-the-page search
box for Feedback Profiles, entering any of the old profiles doesn't locate the
profile the old profile/user name has been merged into.