[Plugin:WP e-commerce]At least one variation is selected

Hi,
Most of things I need I can find a plugin for it. But this one I think it’s involving coding. This is all new to me.

I have 2~3 variation sets for a product, customer only need to select at least one of the variation set, instead of making selection from all the variation sets (default setting).

The box shakes when any of the variation set is not selected.

How do I set the variation to “at least one variation is selected”?
Example link: https://store.amandahsu.com/bonifacio/bonifacio-2/

Help is appreciated!!

Amanda