My friend has a DD who is starting school shortly. The DD pees herself most days. They've taken her to a doctor etc, and basically the issue appears to be that there is no deterrent for doing it (which is what I always expected). Much like my SS, if they are engrossed in what they are doing then they'd rather not have to get up and go to the loo. The parents don't really discipline the child, and I think she enjoys the attention she gets from doing it. She's only really happy when she's the centre of attention, so I think it's all related. All this is an aside really, just wanted to explain that I don't think the child has any serious underlying issues, just that it's behavioural (she's had tests for cystitis etc).
The last time the child visited, she wet herself (narrowly avoiding my sofa) and then, after running around with no knickers on, nearly pooed on the floor (her Mum only just noticed the 'poo dance' in time). I find it super stressful having her over, I'm always on edge wondering if she's going to pee on the sofa (this has happened at another friend's house) or if she'll pee the bed (sometimes they 'put her to bed' at mine so they can stay late).
AIBU? WWYD?