If a child is not taught the meaning of personal responsibility from the beginning, the family has failed in part of its function. That is why enforced sharing is so insidious. It destroys the links between ownership, power, and responsibility. It should come as no surprise that violation of the rights of property by a parent brings with it an immediate punishment. I have seen parents spend whole evenings trying to straighten out what can only be described as property disputes among children.
Children can disrupt the family for so many reasons.
They hit each other, tease each other, knock each other down stairs, compete for Parental affection. So when the property issue is added to the long list of parental harrassment devices, it ought to be shut off from the start. Each child must learn very early that the rights of his brothers must be respected, and that when the parent learns of an infraction, punishment follows with the regularity of a machine. Not that the parent comes in and settles the dispute in a friendly way, but that he comes in and settles it by swift justice. He has nothing to lose and the toy to gain, and his brother knows it.