For starters, you can not play on those areas where there are other kids, but this is not the way. For you is not difficult, if only for a couple of weeks, you will walk with the child together.
At the same time try to follow what is happening in your house in terms of "greed" and "division". Is there anything in your house are things that your child has no right to take? Does the child's things without his consent should not be taken other family members?
Note also how the adults in your family are equality and mutual respect. If adults very often prohibit something to your child, it can also forbid any to their peers to compensate for the fact that he did not give parents. Or conversely, if your child can touch and take everything, he can continue to do it and not the walls of the house.
Most parents give the child everything he demands, when he little one in the family. Also, the child will not understand the equality of the division, if always grown-UPS give him everything, and the only remains of the keep. In such a situation, the child will be very difficult to adapt, because in the home one policy, and on the street adults want from him is quite another.