How to add three names field to the form, "First Name", "Last Name at Graduation" and "Last Name now"?

I am trying to edit the ticket template "Tickets Purchase Form".  I need to edit the subform that takes in the first and last name.  It is for a class reunion and so I need to have the following fields:

First name

Last name at graduation

Last name now

I can't figure out how to either change that subform or create my own subform to replace the standard one