And at 8 months, & 9, 10, 11, etc, are they going to continue to pin him down? Why not let the kid show his age by letting him do what 7 month (or, 8 & 9) old kids do? Stick the sticker wherever it will show and take the pic of the baby being a baby.
He's gonna look awfully silly at 16 years of age lying flat on his back for his homeschool pic.