Controlling International Roaming

I work on an island in the Caribbean with 100+ lawyers.

Our corporate plan with our local ISP has a "roam like your home" where (because the ISP also operate in the visiting country) while travelling, our lawyers can use data "roaming" and be charged for data at the same rate as they would do in our home network. When in other countries (or when connected to other carriers), the same doesn't apply, and we're charged at the high data roaming rates.

Is there a way we can enable/disable data roaming based on geographic location? e.g. I would want data roaming enabled when lawyers are in certain countries but disabled when they're in other countries.