Generally speaking, children don't own property. Property that "belongs" to a child actually belongs to the parents. I have no idea what a "daredevil collection" is or why it might serve as an "investment," but was this property mentioned in your divorce decree? If so, what did that provision say? If not, did your decree include a provision along the following lines: "As to any property not specifically mentioned in this decree, all property currently in husband's possession is conferred to him as his sole and separate property, and all property in wife's possession is conferred to her as her sole and separate property." Such provisions are extremely common (and practically universal). Unless your divorce decree contained a provision specifically requiring your ex to maintain this property for the kids' benefit, it almost certainly belonged to him, and he was free to do with it as he pleased.