Customized iContact sign up form

Elementary school PTA website needs some slight customization to our iContact signup form. Specifically, we use this form so parents can sign up to join the PTA, give us their contact information for the parents and students, and join the email list. In providing the student information we want the parent to be able to choose from a drop-down list the name of the student's teacher. iContact will only allow for 12 choices int he drop-down menu, but we have about 40 teachers. Their support tells me that more can be added, but it must be done via a developer's account and altering the code and I am not a code writer. In future years we would like to be able to go into the sign up form and make any necessary changes to the list of teachers (adding or deleting names).