Here is what i need help with:

I have a parameter for the user to select up to the top 15 vendors by incidents.  So in the data there are 25 or so vendors.  I would like to be able to direct the user to first select the top N vendors and filter the data by that and then be able to only choose a vendor from the previous parameter selection.  So for the below image  select the top N vendors and then have the vendor # filter to ONLY show those top N vendors instead of all the vendors in the data set.  Is this possible?