Discount express shipping once free ground has kicked in?

[Scott_C]

Hi all, Im using the freeoptions shipping module to offer the customer free ground shipping once their cart is over a certain amount.

It works great, and it also shows the express shipping options in case a customer wants the order fast.

What Im wanting to do is to discount the express shipping *if* the free options module has kicked in.

In other words; customer qualifies for free ground shipping, and the express shipping modules deduct their calculated shipping rate by 50% to offer subsidised express shipping.

I imagine that i might need to edit the page; tpl_checkout_shipping_default.php (or even the header file of that page) and possibly the tpl_module_shipping_estimator.php

Anyone have an idea one what part of the code to look at?

I need to find where the shipping totals are calculated and written out, and then i imagine i need to put an if statement around it saying;

if the free options module has qualfied
deduct express shipping options by 50% of their total

Sounds easy in theory.

[Scott_C]

anyone?