Dropdown menus

Now, I know it is possible to make a drop down menu, as I have many in my 3.5 game. What I need to know is if it is possible to put a drop down menu inside another drop down menu. For example, I have separated the skills into 10 categories, each with a drop down macro that allows the player to select a specific skill from that set. What I am trying to do is create a macro that has all ten sets as a drop down. So, for instance, you would choose the Knowledge set, and then be given a second drop down to choose which knowledge skill you want to use at that time. So far I can't get anything to work. It usually just ends up checking every skill on the second drop down rather than just letting you choose. Is there a solution to this?
It is possible, see  Advanced Usage for Roll Queries in the wiki, but it is complicated and usually time consuming.
So, is this saying that to have a drop down in a drop down I need to add & amp: to each of the problematic characters in the second menu?
Thanks. Let me see it if works.