Hi
I have never tried this, but if you have a form with two stages ie 1 and final, then maybe you can add a js field assigned to stage final that triggers the modal. Have you tried this?
Methods
.modal(options)
Activates your content as a modal. Accepts an optional options object.
$('#myModal').modal({ keyboard: false}).modal('toggle')
Manually toggles a modal.
$('#myModal').modal('toggle').modal('show')
Manually opens a modal.
$('#myModal').modal('show').modal('hide')
Manually hides a modal.
$('#myModal').modal('hide')