Thanks for posting those links! I'd watched that first one over and over during the past couple years, because that laugh is addicting. It's nice to see that Dad has her into another airplane, and is all equipped now and she's still loving it.
My guess for the OP is that you can find a parachute maker that will have or will make one that's small enough for some pretty small body frames, and from a chute perspective you can get what you need. From an ability standpoint, I always found that kids can be taught to do most anything with some practice, so make a game of it and run some drills and get them comfortable with the whole concept. Flying in a side-by-side has its advantages when flying with young ones. Will the end result be that you can guarantee that a real bailout will go smoothly? No. But you can certainly push the odds towards the favorable side, and keep legal at the same time. I don't kid myself. I have 2 chutes and brief everyone who rides along for aerobatics on how to use them, but I can bet that there aren't many people, including myself, who are guaranteed to not only have what it takes to pull off a bailout mentally, but become skilled at it as well. We buy the chutes and wear them as a last line of defense, but for most of us it's still a crapshoot that we hope we never have to be tested on. My 2 cents on it is, practice solo, become proficient, wear chutes for legal reasons, but always keep plenty of altitude, especially with passengers, and be good at saving the plane. You're much more likely to be required to use your skills to recover from a botched maneuver than you are to bail out. I doubt that there is anyone on the list that will try to claim that bailing out is a simple option, in any circumstance. But, don't ignore that as an option, and always include it in your briefings.
I bought 2 chutes early on, and bought them big enough for myself to use, i.e. not the smaller chute size but the larger. I find that they fit fine for my daughter who's literally 140 lbs lighter than me. So if you buy the smaller chute model, and have it made for a very small person, you may end up happy with how it fits. Not only that, if you get a seat bottom type, they may be able to use it as a booster seat too.