I honestly think this women thought 'if you dont ask you dont get' and really thought she was more entitled as she had a baby. There are plenty of people like this around these days.
The paying of seats I just dont understand. Pay up when you book or accept that you will have the seats others dont want. I am fed up with people like this and they are everywhere!
A number of years ago I was on a Virgin flight where a women wouldnt sit down until her teen son sat next to the family. He looked totally bored and horrified at the same time. She said the plane wasnt going anywhere until it had been sorted.
In the end the Virgin crew bribed someone to move. Its not right though.