He is too old to be sleeping with his mother.
Not sure how she will respond to her ex, asking her to quit doing this.
So he needs to come up with something like "Hey good news, son now sleeps on his own!"
Also some children need to be given permission, to be given the idea and to be congratulated a lot, for doing what we consider "normal" things.
For instance. Our daughter would wake up early and just stay n her bed. Once she was old enough we told her. "If you wake up in the morning, you are allowed to go to the living room and watch cartoons." Of course we has spoken about not going outside, not cooking.. all of that type of thing..
For the bath, all you can do is follow the same procedures. "I have" filled up the bath, time for you to get in. I will let you play for 5 minutes, then dad will come in and remind you how to bath yourself.
And mom, encourage dad to follow the same routine. Have husband guide "son lets start with your hair. you get it all wet first. of pour just a little bit of shampoo. rub in in your hair real good. Good job, hey do not forget the hair over your ears!!.." Then he gives him the wash cloth and soap start at his face. then his neck front and back then shoulders. Dad help him with his back, then child sons chest.. And do this same thing every night.
Maybe let son know in the morning before you all wake up he is allowed to play with a toy in his bed or look at books, until others awaken.
Remind him of things he can do on his own. Some children do not know how to play because they have not spent enough time allowed to be creative or see how others play. "Son you can go outside and play on the swing set. Here is a towel you want me to pin it to your shirt so you can pretend you are a Super hero?"
You can have him be your helper with the laundry. "Help me sort clothes" Then guide this. "Help me fold the clothes( doe not have to be perfect).
At some point all of you play a board game together. Candyland. Have a build a sandwich lunch. lay out the choices and let him build his own sandwich.
At breakfast let him pour cereal in his own bowl. Let him pull the top off the yogurt. Let him open a package of crackers. He can spread the jam, the peanut butter.. Peel his own banana.
He just needs someone to tell him the rules, how to do things and show him he CAN do things for himself.
Then praise him a lot. You may need to explain to your children why you are doing this.
My stepbrother was exactly like this. It is amazing how you described your step son. He was an only child. They lived in the country. No other children around for him to play with until he started school. They actually lived in 2 houses right nest door to each other.
He became a giant baby. I felt so sorry for him. He would pout.
He would get a glazed look on his face when he was asked to do things for himself.
I recall at a restaurant when his food came he started whining because they had placed the lettuce and tomato on his plate.
He was 9!
He slept with his mother through 5th grade! Icky! And the only reason his father found out was because his son was leaving the bedroom light on all night at the house. They could not get him to turn it off and just use a night light. He was going to be in middle school the next year and was stunted.