XF 1.5 Custom Field- Can I Force Users to Fill it Out

I just added a custom field for Country so I can target my holiday banners to the countries that celebrate them. New users are required to select their country, but is there a way to make all my other members fill this out?
Anyway I can change all my users to have a specific option of a custom field, like a batch update? I am thinking change everyone to "None Selected" and then display a notice to everyone with "None Selected" selected to tell them to select their country to get rid of the notice.
I ended up bulk adding everyone into a secondary group (No country for old men) and the removed everyone we've banned. Put up a notice for everyone in that group to set their country and have since been checking periodically and batch removing anyone who has set their country from the secondary group. Its a pain, but best option I could think of.