I'm actually not sure if this applies to Dreamweaver, but with PHP, you can append the value of multiple variables to one variable. Name your field names with different names, then append them into one variable after you post the form:
$field1
$field2
$field3
--Names of your input fields
$variable
--variable to append data to
$variable = $field1.$field2.$field3;
if you need to have spaces between the field variables:
$variable = $field1." ".$field2." ".$field3;
hope this helps