Fortunately, what you describe does not require a script. It's called a conditional value list. It's more typically done with a drop down list of pop up menu than radio buttons or check box groups as the number of values often varies in size while fields formatted for radio buttons can only display up to a specfic number of values.
Here are some links on conditional value lists:
Forum Tutorial: Custom Value List?
Knowledgebase article: http://help.filemaker.com/app/answers/detail/a_id/5833/kw/conditional%20value%20list
If, after reading all that, you still have questions, don't hesitate to ask them here by posting a follow up question in the Post A Answer box.
I've read the forum tutorial and the knowledgebase article already a little hard to wrap my head around as a newbe.
I'll see if i can use that demo file and figure it out!
Thanks so much for the help,