Multiple Combo box navigation

Hello,

I'm using a master page to allow the client to create multiple "about" pages for each of their venues. This is so they can put pictures of each venue separately as well as opening hours and special promotions only available in certain locations. The design was meant to have two combo boxes, one with a city allowing them to pick the city which in turn would populate the second combo box with the different locations in that city. What would be the best way to accomplish this using perch?

Thank you...