Inheritances in and of themselves are tricky affairs and you are right , one can only do the best one can.
for me, I try to ask "what is the purpose behind an inheritance". Is it really a gift for our heirs or are we using it to try and "control" behind the grave.
Now in my experience, trying to use money to get folks to "correct" what we view as negative behavior rarely, rarely works out well. Couple that with the very truism that once our children become adults they are free to act as they wish, whether or not we like it.
I don't think anyone has a "problem" with op's concern, heck most of us with children share those concerns, I know for me I'm just thinking of the ramifications of trying to use an inheritance to get her son to act how she feels he should act and then comparing them to his sibling.
Now as far as making our children "happy", again pretty much once they hit adulthood, we can wish and pray for their happiness and well being but the reality is, it is up to them.
My questions is a person sets up a trust making the "good" kid the trustee and then kicks the bucket. they are not there to deal with the ramifications and I'd be willing to bet dollars to donughts there will be ramifications.
like I said in all instances I've been involved with, controlling beyond the grave doesn't end well.
In my case I'm not trying to use the inheritance to control or change the behavior. He hasn't been told any of my thoughts, feelings or opinions. It's not nor will it ever be held over his head.
I would bet it's possible that if he was given a windfall and subsequently blew though it rather than accepting the fault was nobody's but his, he'd blame me for trusting him to manage the windfall before he was ready. Some people accept responsibility for their actions, others blame others for what happens to them and have the whole victim mentality. I can't say where my son falls completely but I could see him going either way. Thus I'm potentially in a no win situation so I have to do what I think is best knowing what I've been shown up to this point.