the introduction-story: a big PARENTS problem.

And may be, as you describe it, it became also a UA problem, if the head-steward just neglects/accepts.

I would also book with (hopefully soon grand-) chidren in domestic first (NEVER in 3-class-first) - even more so, as long as the children are very young and have no right for their own seat - than I would need that extra space!

Yes I am also disturbed when children cry for a long time - , but that's life and I ACCEPT it and often (in most cases) I admire their mother/parents for their "work" during the flight. I am never disturbed, but happy, if for example a mother gives her breast to her baby in public (I don't know if my english does describe correctly what I wanted to express).

Their are untolerable exceptions of BAD behaviour of passengers - YES. My personal experience is, 4 out of 5 times it is an ADULT and 20% (only) a child (and their "guilty" neglecting parents). Then I would clearly try to get the head-steward involved - and I would be pretty sure that a majority of other first-/business-class flyers will agree.