@Clockworkbanana Hi OP
Sorry your DD is going through hair-clump horror 🤗
I had long hair (quite fine, but masses of it and wavy) as a child, and would get matted knots and clumps seemingly out of nowhere. They could be from almond-sized to walnut. My grandmother called them "cobs" and would (try to 😂 hah!) chase me all around the house with a bristle hair brush.
My advice to your DD, once the knots are gone, is to use Paul Mitchell "The Detangler" conditioner after shampooing in the shower, every single wash, and comb through gently with an afro comb while the conditioner is still in. It's the best conditioner, a bit expensive but she will only need a little bit (literally a hazelnut-size) if she uses it every day, or at a minimum every 3 days.
Sorry, I seem to be fixated on things being varying kinds of nut-sized on this post..!
But first to get rid of the knots/clumps. As a PP said earlier, I would get DD to sit on a cushion/beanie in front of you on the sofa. Choose a long movie to watch. It's the weekend, so...
Putting an elastic hair-tie between her scalp and the "cob" won't work, because you'd still be pulling on her scalp.
I suggest you hold the piece of hair just above the knot with fingers and thumb of one hand, and pull the clump back towards her scalp, rest your fingers on her scalp while holding tight above the knot, so there's no tension. With a pick, or a prong of the afro comb, gently pick and pull. X