I would draw all the lines you want and then label them so they can be individually treated. Then you can flip their 'visibility' property with your code. This is far easier as you don't need to fiddle with their endpoint locations and colours/width/pattern etc in your code.
An example showing how easy it is to toggle visibility on a couple of lines is below
Code:
Sub HideALine()
With ActiveDocument
.Shapes(1).Visible = Not .Shapes(1).Visible
.Shapes(2).Visible = Not .Shapes(2).Visible
End With
End Sub