How to snap two custom shapes together WPF

I created custom shapes in XAML and I'm trying to connect them together like in the image <a href="https://drive.google.com/file/d/1wmN6jMAnmEmROCT1b8r4WZEkERNWr48T/view?usp=sharing"></a>
they can connect only if they are Compatible. Could you help me in solving this problem, please? 

The XAML code

<Canvas Height="485" Width="500" Margin="0,-1,131,0"  Background="LightGray">
        <Path Stroke="Black" StrokeThickness="2" Fill="Aqua">
                <Path.Data>
                    <CombinedGeometry GeometryCombineMode="Xor">
                        <CombinedGeometry.Geometry1>
                            <RectangleGeometry Rect="20,30,250,80" RadiusX="10" RadiusY="10"/>
                        </CombinedGeometry.Geometry1>
                        <CombinedGeometry.Geometry2>
                            <CombinedGeometry GeometryCombineMode="Xor">
                                <CombinedGeometry.Geometry1>
                                    <PathGeometry>
                                        <PathGeometry.Figures>
                                            <PathFigure StartPoint="85,110" IsClosed="True">
                                                <LineSegment Point="75,120"/>
                                                <LineSegment Point="50,120"/>
                                                <LineSegment Point="40,110"/>

                                            </PathFigure>
                                        </PathGeometry.Figures>
                                    </PathGeometry>
                                </CombinedGeometry.Geometry1>
                                <CombinedGeometry.Geometry2>
                                    <PathGeometry>
                                        <PathGeometry.Figures>
                                            <PathFigure StartPoint="85,30" IsClosed="True">
                                                <LineSegment Point="75,40"/>
                                                <LineSegment Point="50,40"/>
                                                <LineSegment Point="40,30"/>

                                            </PathFigure>
                                        </PathGeometry.Figures>
                                    </PathGeometry>
                                </CombinedGeometry.Geometry2>
                            </CombinedGeometry>

                        </CombinedGeometry.Geometry2>
                    </CombinedGeometry>
                </Path.Data>
            </Path >
        </Canvas>