Heather, what about modeling the proper behavior for S4 by using it with D2 and H. Just start doing it. "Good morning D2, how are you today?" "Good Morning Daddy, D2, tell Daddy good morning" You could even ask S4 to help you teach D2 how to do this. "S4, when D2 wakes up, I want you to tell her good morning and give her a big smile. This will help her learn good manners"
One thing my counselor suggested for us was to ask H's assistance with behavior problems. My middle daughter, 6 years old, seemed to be having problems, trying to get attention, even negative attention, so she suggested this..."H, you know, D6 has been acting up, demanding attention...what do you think we should do about it?" He came up with the idea I had already thought of, but having his involvement, was supposed to help H feel more connected and involved.
You could say, "H, I think we need to work on S4's manners. What do you think we could do to get him to be more courteous?"
I agree that kids learn these behaviors early on, and that you do have time to turn him around.
I have a kid upstairs, it's almost 11:30, who just wants to go to sleep, "Daddy lets me sleep in the chair at Grandma's house. Daddy loves me more than mommy. I just want to go to sleep and Mommy won't let me." "I want my Daddy, Mommy doesn't love me." Silly me, I put her in a bed, how was I to know she'd rather sleep in a chair? So, I am in full re-training mode. It's almost time for school to start up again and I have an 8 year old that has never learned to go to sleep. WTF do I know?
Good night Heather and good luck. Hang in there....
Each experience in life has formed me, become part of me, made me stronger.