Add a form between shipping method selection and order review I'm coding a custom module to make shipping by a delivery enterprise which is not having a module compatible with Drupal commerce.

So, I give the customers a choice between 2 shipping methods:


colissimo (a French official delivery method) using an existing module
exapaq using the custom module I am trying to create


This is working, but exapaq doesn't deliver to customer's home; it delivers to stores where customers can have their order.

So, after customers select the shipping method, I would like to test which is selected and, if this is exapaq, add a new form to allow customers select the store to take the order.

The problem is that I don't have any idea on where can I do this test and how I can insert a new form before to go on order review page.
The payment panes makes this kind of interaction possible through a "details form" that open when you select the payment method that has this configured, and this is great because everything happens on the same page via ajax. But i don't know if Commerce Shipping has this too.
If not, i think that the best way for you to make this is to create a Checkout Page specific for your Shipping Method and create a Checkout Pane with your form to be in this page.

You can take a look at how https://drupal.org/project/commerce_correios handle this situation, because it's a Shipping Method too, so the API should have a lot in common with what you need.