All of these responses have been good food for thought.

When I look back on my original post- it seems I have 2 issues which I may have been rolling into one.

1) My nephew's behaviour

2) When to end the monetary gift giving.

I cannot do anything about his behaviour. I can end the gift giving at a certain age for all nieces and nephews. Which I think would be fair all around.

Thanks everyone for your thoughts and insight.