I have a grid connected to a ViewModel class with two properties, public Address SelectedAddress and public ObservableCollection<Address> Addresses.
Address has, among other things, int? PersonID and int? CompanyID. My validation code in the Model checks that one of them is filled, but not both.
How do I set up code in the grid or ViewModel so that whenever PersonID is filled, CompanyID is automatically set to null, and the other way?
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