Totally agree with this. Own life jacket first etc @Rainbow03
As for what is motivating demand avoidance and controlling behaviours, and how to reduce them, this is such a complex area.
I have cracked this one with my own ASD child. It has required a very nuanced interplay between implementing a lot of structure and predictability but making it feel to my son like he is in control. Choice mechanisms and logical, natural rewards and consequences at every stage. Never, ever 'because I said so.'
At age 4:
6.30 is bathtime. If we can get into the bath and out by 6.40 there is time for an extra story. Would you like an extra story? What extra story would you like me to read? Lets choose that now, and then we can bring the little clock into the bath to check we are still on time. (At 4, he didn't know to argue for a later bedtime, as this was on the visual timetable which was, in his mind, predictable and immutable.)
Now, at age 11:
Bedtime is 8.30 to get up for school on time. It can be 9 if you want but I guess you might need to sleep an extra 30 minutes, and then we might miss the school bus and you could get a late mark. Remember if there are three late marks in a month at school you have a detention. What would you like to do? Whatever you choose is fine with me. (At 11 he does know - and love - to argue for later bedtime, so school rules are our best friend).
But this is only one case of one child - mine - and I would only ever direct another parent tackling PDA to 1) get some respite then 2) get some help.
Once the behaviours are entrenched, this is evidence that can be supplied to the GP, hopefully for a CAHMS referral.
One child of a close friend went from PDA to ODD, then CAHMS. What came back was that he needed way more structure, rules and micromanaging of rewards and consequences. He's been put into air force cadets and loves it.
@SpecialMangeTout 's reference would support this.
But another family I know found that going low/no-demand was the only way to get their daughter to eat a meal or leave the bedroom. They have decided to home school and luckily have the financial means to do so.
I found this book extremely eye-opening and helpful, written by the mother of a girl who had a very strong PDA profile:
www.pdasociety.org.uk/resources/pathological-demand-avoidance-syndrome-my-daughter-is-not-naughty/