In the matter of making a small child sit in it's own allocated seat ... and the statement by TS that it was sometimes necessary to mix the rules when you are already long into the descent.
LHR ~ GVA on Swiss about ten years ago - the flight is seared into my brain. Daylight and good weather for a lunch time sector.
I was in 'C' on the Starboard side of three seats. I had the window. A well dressed woman was in the aisle and the infant, about four I think, was between us. Throughout the two hour flight, he was perfectly well behaved. Until it was time for seat belts ...
He kicked and screamed and crawled around the floor. I was astounded at the change in him, the child was two characters. The mother worked very hard to mollify him and the CC did their best. I helped to drag him off the floor and put him in the seat and two of us had to put the belt on to him.
For the last minutes of descent, through to the roll-out, his mother held him and tried to passify him and I held onto the buckle so that he could not release it. He screamed loudly throughout, thrashing around in the seat.
Once we were taxying in - the other child reappeared and he was calm and quiet. The mother was most apologetic but I said that I could see that she had done all that she could. The CC gave me a big Thank You.
Thus, I have no doubt that the action that senior CC may occasionally have to take, by allowing a child to be in a parental lap, is valid. The child's behaviour at departure and approach were utterly different and the hysteria could not have been anticipated. In this case, the law was followed but the noise and disruption to the whole flight was significant. If the child will not be restrained and the parents will not hold it down - then let it be in the aisle and take what's coming to it.