[nulltone]

Go to http://bulletin.sagehillschool.org.
This is the bulletin board for my school. I administrate it.
Ok, here is the deal. For usernames, I make students use the school networks usernames, to keep things ordered. So, a John Smith's username would be "smithj", which is quite unpleasant. After enough complaints, I came up with an idea.
I made a custom profile field (in my case, "field5") called "Name". Students enter their Full Name "John Smith" in this field. I then replaced all the username variables with "field5" variables in the postbit templates. This works fine.
But from the forum display, and all the other areas, it shows the username. How can I make it show that users "field5" instead of the username? Which variables do I use in the other templates? Does this require a complex hack? What about "Last post by...". Can those display "field5"'s for usernames too?