I would put each form as a function and each submit process as a function. As you work your way down the pages you just call the next from function... That way you can do everything on 1 page... i.e.
function 1st_form(){
form
}
function 1st_form_process(){
db add
2nd_form()
}
function 2nd_form(){
form
}
function 2nd_form_process(){
db add
3rd_form()
}
etc etc