Thanks everybody for replying to my questions.
Since I will alter the shape of a flsheet that I have, I want to reinorce some corners.
The material is ripstop, so I wonder, What is a good way to reinforce ripstop at those places where the straps are connected.
I thought about sewing a triangular form on the area, then sew the whole area.
But do I have to use the same material ( as the flysheet )for this triangle?