Zip lock bag for boys peeing. Zip it up and dispose at earliest convenience. For girls peeing and for more solid matter, plastic bag with a disposable diaper or feminine napkin inside. We keep an inflatable potty in the car and carry it deflated while hiking along with several bags with diapers inside. I am thinking of getting an adult duty inflatable potty to replace our kiddie one that we have had for years. Then the kids (and wife) can use it in the tent when it is raining cats ands dogs and they don't want to venture out.
Pee to treat stings when nothing else is available.
Enough of the pee.
Carry a SAK with some cordage as a fob as EDC. That has saved the pinata portion of a kid's birthday party once when the mom and dad couldn't hang up the pinata. The fob was unraveled, the pinata was jung, and MacGuyver saves the day.
Also saved my butt, err feet, when I was showering in camp and my slipper broke. The string made a good field expedient repair to get me back to my tent.