Do not - repeat, DO NOT - try to remove the red cast. It belongs there, it's meant to be there, and the photo would look darn weird without it.
Instead, make the flag redder. Own the cast.
Give me a few minutes, I'll post something.
Whoa.
For future reference: http://www.damiensymonds.net/2010/09/extract-then-copy-vs-copy-then-extract.html
For now, I suggest adding a Levels layer above the dad layer, and clipping it thereto (Ctrl Alt G). Then change the Levels layer's blend mode to either Soft Light or Overlay, and see if you like the slight extra punch.
Oh gee, Stacey, that's a gift, use it. Your Grandad's feet are at a plausible angle that your Dad's are not. I'd try to use GD's feet, and merge the two men mid-leg if at all possible. It wouldn't be easy, but it would DEFINITELY be worth it.