If it's repetitive,
it can be automated.

public class Customer : INotifyPropertyChanged
{
    private string _firstName;
    public string FirstName
    {
        get => _firstName;
        set {
            _firstName = value;
            OnPropertyChanged();
            OnPropertyChanged(nameof(FullName));
        }
    }

    private Address _address;
    public Address Address
    {
        get => _address;
        set {
            if (_address != null)
                _address.PropertyChanged -= OnChildChanged;
            _address = value;
            if (_address != null)
                _address.PropertyChanged += OnChildChanged;
            OnPropertyChanged();
        }
    }

    // computed: re-notify it by hand
    public string FullName =>
        $"{FirstName} {Address?.City}";

    private void OnChildChanged(object s,
        PropertyChangedEventArgs e)
        => OnPropertyChanged(nameof(FullName));

    public event PropertyChangedEventHandler
        PropertyChanged;
    protected void OnPropertyChanged(
        [CallerMemberName] string name = null)
        => PropertyChanged?.Invoke(this,
            new PropertyChangedEventArgs(name));
}