It isn't the main part of the pants, but that 4 inch strip of stretchy material that runs down the butt and the inner thighs. I tore a nickel sized hole in butt of my pants when they caught on something hopping the boards. I want to repair them before it gets worse. Has anyone had any experience fixing this part of the pants. I want to fix, all while the same time leaving it somewhat stretchy, but not come undone as well. I appreciate your help. Thanks.