User Registration Form

[NZSolutions]

hi there,

my client is a franchise located here in nz. they have franchisees throughout nz and australia, and also stores in asia (1 presently).

i am setting up there shopping cart application. one of the requirements is that when an order comes through it is diverted to the relevant fanchisee based on that stores coverage.

now i am a little unsure how to structure the user registration so that their billing details ensure the order goes to the correct store.

lets say store abc is in newmarket, auckland, nz and store xyz is in ponsonby, auckland, nz. then other stores might not be in cities but small towns.

what i need is a registration form that drills down depending on the users selection. i am aware of dependent select boxes, but this would be a little in reverse eg.

select country ->
if australia - select state ->
select town/city ->
if major city - select suburb

if anyone has worked on anything like this before i would really appreciate some advice.

regards
mike