if I have an intersection that I want to match up I'll pin until I get it just perfect then go to the machine and "pre-sew" just that place with a few stitches, then sew the pieces together just like normal. When I get to that intersection, it's already sewn so I know it's not going to shift or move and any adjustments can be made before or after that spot. I just sew right on over those few stitches as if they weren't there.