>>197195
Long retired now, but back in my days in the 70s, I used to do family photography at first, then met some "open minded" groups that wanted risquè photos of their daughters. I had to throw many of the prints away years ago because considered illegal today, but I did nothing more than what the photographers had published officially by Playboy back in the day, like the famous 10yo Brooke Shields photoshoot. All in all, my style of children photography was similar to the portraits taken of Eva Ionesco when she was very young.
But to answer you question on how you do it nowadays, it's simple, don't even try if you are a man, they will breathe down your neck and it's impossible. Unless you get into wedding photography, and AT MOST, out of thousands of shots a week, you manage to squeeze a couple of the couples' daughters in a dress.