I am hanging 1/2" drywall in my 1st floor powder room. Between 2 studs is a forced air duct that goes to the 2nd floor. It sits flush inside the stud wall except toward the bottom where a seam is located to join 2 pieces of ductwork. This seam sits out beyond the studs by approx 1/4" ---- the seam is about 11" wide x 1" high. Is it OK to carve out the back of the 1/2" drywall to fit over the seam? My other thought was to shim out this area and use 1/4" drywall then butt the 1/2" up to it. I hate to go this route and have extra taping and a "bulge look" in this area.