I am needing to add a shipping module based on one available already in zen cart- freeoptions.

I use this to offer free shipping to my customers once they reach a certain order total. The way I have freeoptions set up is I only allow the free shipping to appear if the weight is also 13ozs and under. So, basically they get free first class shipping but not free Priority if that is what is needed to ship their package.

I want to make a change that offers reduced and partially free shipping if they are over 13ozs. I want to offer a flat rate Priority charge of 2.00-2.50 if their cart total is over a certain amount AND weight is over a certain amount, then they are presented with the REDUCED Priority option. If both conditions were true before they were simply presented with our flat-rate Priority option, but we want to instead, in this situation, offer a reduced flat rate Priority option.