Datagrid Tables within Tables

Question

I'm trying to show a datagrid that has multiple relations. What I have are categories and within each category a set of options that are selected via checkbox. In the Microsoft example, using tree type navigations, you have to open the category (+) and then click a link which takes you to the options grid. I want to be able to expand and collapse the options without going to another grid ex: + Category 1 - Category 2 Option A Option B Option C + Category 4 + Category 5 ... Does anyone have any samples on how to do this?