suppose A is first registered and depends on X, then B is added and depends on X, and then C is added and depends on X, then A is the elder sibling to B and B is the younger sibling to A, and B is the elder sibling to C and C is the younger to B
suppose A is first registered and depends on X, then B is added and depends on X, and then C is added and depends on X, then A is the elder sibling to B and B is the younger sibling to A, and B is the elder sibling to C and C is the younger to B