Hi K.,
I'm in my 50's and raised two children, as well as taking in foster children when they were younger. We also had some competitiveness and unhappiness with having other kids around so much (not something I'd do again looking back, when the kids were young). But I'll suggest a couple of things that could help.
You mentioned consistent discipline for your son...excellent. But when you use discipline with him, try getting down on his level, eye to eye and drop you voice to a very soft tone, where he has to really listen. After you've talked to him, ask him (and this is something I'd do all the time, not just when the other kids were around) to respond to what you told him with "yes mom" or something similar, making sure he understands. It also helps teach them a greater level of respect. Have him repeat back to you what you asked him to do as well. Then PRAISE him for listening and let him know that you're very proud of him as you know he can do it.
That's the second step. Every time he does something that's good, no matter how small (while at these people's home) praise him in front of the other children. Let him know what an excellent helper he is to you and when he's being good, point to him as an example of how the other kids should do (whatever he just did)...in other words, brag on his good behavior.
I'm guessing that he's mostly just competing for your attention, as he's used to being the only child and focus of your attention. Now he's having to share you with three other kids. If he only gets individual attention by being naughty, he'll continue. But if he starts getting heaps of attention whenever he's good, he'll find more ways of being good.
I hope that helps a little...I'd love to know if it does, so feel free to drop me a not if you'd like.
M. Ferrell
____@____.com
http://www.miraleeferrell.com
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