The child's business is an s corp for which he is an employee and the 100% owner.  As long as thereis an accountable plan, the child's s corp can reimburse himself.  The property itself isn't owned by the S corp nor is the s corp trying to reimburse a non-owner.  The property is owned equally between the dad and the son.  

I have read that S corps can  reimburse depreciation. 

 https://www.journalofaccountancy.com/issues/2020/feb/employee-expenses-accountable-plan.html

Journal of Accountancy says "Home office, Including depreciation".  Thoughts?