She only asks over and over because she is ignored over and over, if they were to answer her the first time she asks and say they were busy she would soon learn that not everyone wants to play all the time.
Really? Is this your first child OP? I do agree that the SC should not be unkind, but I think your expectations are too high. With my own DC, they never asked once, were politely told "no" and then went on their way.
Never. Not at three. Not at five. Not at eight. etc. What actually happens is asking again, and again, and again. Usually with some physical contact thrown in to stop the other child from whatever they are engaged in. It soon ends up in a squabble, if not a wrestling match. Hey presto, the child wanting the other's attention gets it. It may be negative attention, but it's attention. Not long after, I'm called in to hear a lot of bickering about "who started it!"
Reading your posts and expectations, I would think that I was a particularly inept mother, except in real life, this goes on in all the families that I know with more than one child.
A lot of us would gladly settle for "ignoring."
Given the complexity of the family situation you have, it could be a lot worse than ignoring. Pushing for more interaction could back-fire.
I think you have a right to not like the dynamic of this situation for your own child. It may be best to walk away from this man and all that comes with him. Sometimes things just don't work, even if you love them.