1) Overlapping here mentioned :
2) Code Here:
I need to avoid arrowhead overlapping issue whenever we select the link. it should be highlighted with arrowhead.
Since you seem to be showing that a Link is selected by changing the color of the Shapes, you don’t need the standard selection Adornment which is a dodgerblue Shape extending the length of the route. So first I would set Part.selectionAdorned to false on the Link template.
Second, the path Shape (the first Shape in the Link) presumably will never have a Shape.fill, so there’s no point in having that Binding. So I would delete it.
Third, since Shape.strokeWidth is zero on the arrowhead Shape, the Binding on the Shape.stroke property is useless. So I would delete it too.