Get the value of a radio input before that submit the form.

[eluser]PhilTem[/eluser]
This should actually help you and work for you as long as you adopt the markup (i.e. the IDs to match the IDs of your items you want to work on)

https://gist.github.com/4319986

If you need something else, at least for me you'd need to rephrase your question since I don't see if you want to manipulate the form before submitting or when selecting something on the radio buttons and then append another select depending on the value of the radio-item selected.