I don't think that it looks badly the way it is. If you are bound and determined to replace the "pink" fabric - my suggestion is rip it out (imho).
Using SteamaSeam will change the actual feel of the blocks in my opinion and if you plan on switching the fabric out in the blocks that are currently unmade the difference in feel and drape will be apparent. If you rip out the sides - it will only take a few seconds more to remove the piece completely and you might be happier in the end. You will only need to rip just past the seam allowance to replace the square and it should not distort the squares at all.