I think I would take the offending blocks out one at a time. Just open up all four sides and change the way you need to. An easy way to take out a seam with out distorting it is to use a seam ripper or a very pointed pair of small scissors. and cut about every 4 or 5 stitches. Then flip the seam to the other side and pull up the thread. The whole seam will come loose very easily.