Excel 2007 : Help with lists on multiple tabs, in different orders

Hello,

The issue I'm having seems like it should be simple, but I have had no success. My issue is this:

I have a database with customer lists on multiple tabs. These lists are sorted differently for specific reasons. All I need to do is be able to place an "X" in a column next to a customers name, and have the "X" automatically generate next to the same customers name on the other spreadsheets.

What formula should I be using to accomplish this?

I would greatly appreciate any help!

Thanks!!!