if it doesn't buff out, you haven't lost more than a few bucks. Pay a shop to do it if you don't feel comfortable. 3M makes good stuff, others are available.
I say try and buff it out.
Whip the lil one, or take them and let them see you "sell" their toys to fix it. (just take them to someone elses house and pretend to sell the toys to fix the mustang)
Heck I got a lil bitty dent in my fender and a chip.. that's when my car went from been factory stock and perfect to a dirty damaged goods... It's so much more fun this way..
I had a dark blue truck that I took off roading even though it was 2wd and went through all kinds of bushes and it was scratched all over the place like it was keyed by 20 people. I took it to a detail shop and the buffed them all out and you could never tell it was scratched.
The pics don't look too bad -worthy of a spankin' to the little one no doubt..
Stop by the body shop and see how much a good buffing will remove. I'm confident you'll still be able to see the scratches a bit, but it should be much easier on the eyes afterwards. Keep the hood, keep the paint, and get it buffed.