Wow! Re your post starting "ah bath time" you have HUGE issues with this child isn't having their boundaries enforced, they're confused and scared and acting out as a result. I suspect this is due to you and dh having such different parenting views. And frankly I susoect dh being too lax is why you're having to be the bad guy. Actually I kinda HOPE that's the reason - because yet again these are red flags of a child that's been abused. I used to barricade my bedroom door!
No more pissing about! You need to contact GP/hv and ss ASAP and get proper professional support for your whole family.
This CANNOT continue like this!
"I rarely see him do it out of the house" because he DOES know it's unacceptable behaviour and CAN control himself when he WANTS to.
"Winding people up" - is not just attention seeking its aggressive and controlling at root. It's enjoying the ability to make another person feel bad. This is NOT something you can allow to go on being not corrected by your dh! It's also ANOTHER red flag re abuse.
"His friends and sister he seems to think of as "his" " so he's objectifying them and viewing them as his possessions. Fuck it gets worse!
You need to get this child seen by an expert. No I'm not biting my tongue any more its SCREAMING out of him! Something serious is going on here. You NEED To know what and get it dealt with.
I'm no expert but I believe If there was a pathology causing the lack of boundaries he wouldn't be able to control it ever, yet you say he can sometimes.
I too am beginning to wonder if this post is genuine. Assuming it is:
Red flags he's been abused:
1 Inappropriate sexualised behaviour which he can control and is able to limit.
2 Resisting bed time so strongly
3 Resisting bathing strongly - except when it can be used to delay bedtime
5 Objectifying others
6 Lacking empathy for others desire for bodily autonomy...
7 ...while fiercely protecting his own.
8 Getting pleasure from causing negative feelings in others.
If true this child needs a sw and a therapist imo.
I suspect I'll now get posters saying I'm overreacting, that any of the above don't necessarily mean there's a serious issue here. Well if there were 1 or 2 of those issues I'd probably agree but 8!!! The more op posts the more it looks increasingly likely that something very serious has either happened to, or is affecting this child.