The reason I'm trying to understand the need for the session variables is that maybe the lines that initialize the variables should be something like this:
$sessFirst = (isset($_SESSION['First']) ? $_SESSION['First'] : "");
$sessLast = (isset($_SESSION['Last']) ? $_SESSION['Last'] : "");
But the bigger issue that I'm not understanding is where these variables are being set. If this is Form 1, then those session variables aren't going to be set when the script is executed, so they will always be blank.
As a test, try replacing the initializing of the variables with this:
$sessFirst = (isset($_SESSION['First']) ? $_SESSION['First'] : "First Name Not Set");
$sessLast = (isset($_SESSION['Last']) ? $_SESSION['Last'] : "Last Name Not Set");
If you run that, and it shows "First Name Not Set" then you know that the data isn't being passed, which means that you have to look at the form that is calling this page and figure out why the data isn't coming through.
EDIT:
If you e-mail me your files I could take a better look at it, if you want.