Show free shiping with other shipping op

for osCommerce Online Merchant v2.3

I was looking for an addon to allow customers to a select free shipping option when the shopping cart reaches a certain value. i.e. when £50 or more is in the shopping cart. The total orders module provides the free shipping option, but the other shipping options were not displayed when this criterion was reached. I'm currently using 2.3.4BS Gold, but the addons available to give me this option didn't provide a solution without a lot of code changes. This addon uses the table shipping method to address this issue.