// Исходный класс.
    public class FlyProject: INotifyPropertyChanged
    {

        bool _isPolygonMode = false;

        public bool IsPolygonMode
        {
            get { return _isPolygonMode; }
            set 
            {
                if (value != _isPolygonMode)
                {
                    _isPolygonMode = value;
                    NotifyPropertyChanged("IsPolygonMode");
                }
            }
        }

        int _bp = 0;

        public int Bp
        {
            get { return _bp; }
            set
            {
                _bp = value;
                this.NotifyPropertyChanged("Bp");
            }
        }

        List<Point> _pathPoints = new List<Point>();

        public List<Point> PathPoints
        {
            get { return _pathPoints; }
        }

        public FlyProject()
        {
            // набор точек для примера.
            _pathPoints.Add(new Point(50, 75));
            _pathPoints.Add(new Point(100, 30));
            _pathPoints.Add(new Point(70, 15));
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void NotifyPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
    
    // Класс-обертка
    public class FlyProjectContext: INotifyPropertyChanged
    {

        FlyProject _project = null;
        public FlyProject Project 
        {
            get
            {
                return _project;
            }
            set
            {
                if (_project != null)
                    _project.PropertyChanged -= _project_PropertyChanged;

                _project = value;
                _project.PropertyChanged += new PropertyChangedEventHandler(_project_PropertyChanged);
                
            }
        }        

        public FlyProjectContext()
        {
            Project = new FlyProject();
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void NotifyPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }

        private void _project_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            this.NotifyPropertyChanged("Project");
        }
    }

    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        FlyProjectContext _projectContext = new FlyProjectContext();

        public MainWindow()
        {
            InitializeComponent();
            this.DataContext = _projectContext;
        }
    }

    <Window.Resources>
        <c:PathPointsConverter x:Key="conv1" />
    </Window.Resources>
    <!-- ... -->
        <Canvas Width="350" Height="200">
            <Path Stroke="Black" Data="{Binding Path='Project', Converter={StaticResource conv1}, Mode=OneWay}" />
        </Canvas>
     <!-- ... -->
    <TextBox Text="{Binding Path='Project.Bp', Mode=OneWay}" />