Stubborn tangles

This is about my SO's 8 year old but the parents of curlies forum is so slow so pardon me for posting it here. She has 2a/b waves, fine-medium texture, and it's dense. I wouldn't say it's VERY dense but it's dense.

She has the most insane tangles I have ever seen. My hair is much curlier than hers and does not tangle like this. At first I thought it was because SO is a single dad and literally did not know what conditioner was until I met him, so I spent a few months using much gentler shampoos on her and deep conditioning it. Then I found out she hadn't had a trim in 2 years so I took her to get her split ends trimmed and some long layers put in.

Ladies, I am at a loss. I wondered if her hair was low porosity and just dry, but it does not behave like low porosity hair. It doesn't take a long time to get wet and doesn't take a long time to dry. When it is soaking wet and full of conditioner, I can sometimes use a wide tooth comb and get them out and sometimes I can't.

Once she's done showering, if I am very careful helping her rinse it out and make sure she doesn't touch it with a terry cloth towel and we put some LI in, it is okay for a few minutes. But once it's dry, all bets are off. I'd say it's about APL and from her shoulders down (which, coincidentally, is where her strongest wave starts) it is impossible.

I know you're not supposed to comb dry hair, but if she gets it wet when it's tangled like it does, it makes it 10x worse. It will mat up like a spiderweb and create knots. So I'll start at the ends of her hair and very gently try to finger comb it or wide tooth comb it and I'll get a 2" section tangle free and by the time I get to the next section, the first section is tangled again and all she's done is stand there! WTF? Mornings are awful. More days than not she goes to school with ratty hair to be honest :(

She goes to her mom's every other weekend and sometimes will spend a weeknight with her aunt who has helped raise her and I can't control nor do I know what they put in her hair as far as conditioners go, so every other week or so I'll clarify her hair in case there's cone build-up. Having the hair I do, I figured I'd seen it all and I tried everything I knew about moisturizing hair. I've avoided protein with her. I don't have issues with tangles like this. Even her hairdresser when we got it trimmed, who has natural curls herself, was baffled. What causes this? Ideas?
:wave: fine, thin, normal/(low?) porosity. Mod-CG. Usually I can't co-wash more than 1x a week, & sometimes I have to use T-Gel in rotation due to scalp issues.

Co-wash: VO5 Volumizing
Poo: Giovanni 50:50
RO:TN, Nexxus Youth Renewal, Alba Coconut
PT: gelatin PT, ION EC
Stylers: Giovanni mousse, TIGI Curls Rock amplifier (a-cone), Curls Rock Strong Hold Mousse
Gels: SCC spray gel