Hully - I've just re-read all of your posts, just your posts and no one elses.
Your posts could easily be addressed to me right now, with my DS1's battle at the moment.
And I would have found your comments extremely annoying if they were addressed to me - but not goady or sanctimonious, you're right there.
My DS is pushing the boundaries, and yes, you're right, there is a reason. The reason isn't abundantly clear, I'm making attempts at working them out and I think I have some of them sorted, but some of it is his personality and the way he deals with issues.
Right now he is trying to control everything, and I mean EVERYTHING. Doing my absolute head in, and very upsetting for his younger brother. And the tantrums, oh my word those bloody tantrums over every sodding thing.
I have tried to address it by giving him more control over a number of things, but I still hold firm to the boundaries. Regardless of how he feels, I will NOT accept being spoken to rudely, I will not allow him to control his younger brother, he does NOT get to decide each and every meal this family eats, he does NOT get to decide each and every activity, etc, etc.
If he throws a tantrum because things don't go his way when we're out, then either the activity gets cancelled, or some other treat will get cancelled (I mean tantrum, not just a small strop btw)
Why is he trying to get control? I suspect school is partly to do with it, he is being pushed more now (Yr 2) and has less free time to do what he wants with. He's very capable but fears getting things wrong and just doesn't like trying new things, so has to be almost forced to do things at times (oh what great fun with the SATS preparation right now....). He's very sensitive to issues with friends, and that's another whole difficulty there due to certain other children at the school.....
So yes, lots of reasons. But at the end of the day the reasons, whilst important, don't actually matter to the day in, day out activities, boundary setting, rules that need to be followed etc.
I can understand why he's upset till the cows come home but I will not be screamed at by my DS because he doesn't fancy roast chicken that evening.
If he screams at me and throws a tantrum, then there is a punishment for the tantrum, regardless of the REASONS why he is tantruming (usually time along in his room, maybe missing out on a small treat). He is being taught that actually, there are other, much BETTER ways, of dealing with things that he feels are an issue.
So yes, there may well be reasons, but the reasons are actually almost irrelevant to the OPs, post, ie that in THIS circumstance, she was NBU to deny her step child ice cream, regardless of WHY her step-child is behaving this way. A consistent approach to negative behaviour will actually be MORE helpful in dealing with any possible problems she will have.