Hello and welcome to BYC!
Glad you joined.
I'm so very sorry about your son.
You can winterize their run by covering all but the top few inches of the walls with a clear shower curtain or tarp to block the wind and snow. Obviously having a solid roof on the run helps greatly in the winter.

I'm so very sorry about your son.

I would avoid doing that. The water will build up moisture in the coop which increases the risk of frostbite.Is it ok to put the feed and water inside the coop ( it's in feeding bowls) during the times, like today where they refuse to come out in the winds cold and snow?
You can winterize their run by covering all but the top few inches of the walls with a clear shower curtain or tarp to block the wind and snow. Obviously having a solid roof on the run helps greatly in the winter.