1) It comprises of two drop down boxes, one is the 'category' the other is the 'sub category'. The values in the sub-category box need to change depending on what category is selected.
2) There also needs to be an 'Add Row' and 'Delete Row' button. The 'Add Row' button will duplicate the drop down boxes, allowing for another selection to be made. The 'Delete Row' button will remove the last added row (unless it is the only row, in which case it does nothing).
3) Finally I will be using this form to send an e-mail using a PHP script that is attached. Therefore I need the variables to remain the same.