Search Engine Help

I've been working on a Display Name hack that allows people to have a displayed name that automatically overrides their username if it exists (with protections to ensure that noone can choose a DisplayName that is either already in use, or is the same as another user's username).

This added a field to the user table: user.displayname

In the searches in the memberlist, I handle the sort order of names by using a concatenated string of CONCAT(user.displayname,user.username) as my sort key, as the end result of that operation would leave only the username if the displayname is blank or null.

I'm at loss now when I get to the search engine... to be honest, it's got me completely confused..... I managed to get it to bring up the correct results in searches based on username, but I'm at a loss when it comes to two things...[list=1][*] is the display of the actual thread within the search engine... I'm not sure which of the queries it is, and[*]... where am I supposed to drop the new field in and change my sort key to the concatenated one?[/list=1]

Attached is an unfinished copy of my hack containing only the necessary pieces to actually see what it's doing in the memberlist and search engine, as well as to add the field.

Any help anyone could offer would be much appreciated.