Select only childs contained inside its parent

Select only childs contained inside its parent

Hello,

I created this simple jquery -> http://jsfiddle.net/psytanium/6D9kS/401/

I'm very beginner with this language, I'm trying to clear all check boxes when "All options" is checked, and vice versa. I'ts working fine, but it is affecting the other forms too.

The problem is I have multiple forms, I need to apply this script to each form separately.

Thanks :)