Subcategories display in "category field search"

Hi,
Is there anyway to show subcategories of subcategories in "categories dropdown field search"?

I think on admin if you go to edit listing type, there is somewhere where you can choose how many levels there are on the search forms

Thanks for the suggestion. But it take a lot of time to click and select 3 times to get to the subcat of a subcat. Is there anyway to add it into the normal drop down? That way it will be much easier.