Do you need to use 2 parameters? Could you use quick filters instead and select 'Show Only Relevant Values' in the Sub-Category quick filter?
Thanks for your response. I have two quick filters working with the quick filter sub-category list of values showing a subset of values based on what category quick filter value is selected. However the quick filters take up more space so I wanted to use parameters instead. Is there a way of controlling the dropdown list of one parameter based on the selection in another parameter?