In this paper we investigate the problem of providing consistency, availability and durability for Web Service transactions. We consider enforcement of integrity constraints in a way that increases availability while guaranteeing the correctness specified in the constraint. We study hierarchical constraints that offer an opportunity for optimization because of an expensive aggregation calculation required in the enforcement of the constraint. We propose an approach that guarantees that the constraint cannot be violated and also allow the distribution of write operations among many clusters to increase availability. In our previous work, we proposed a replica update propagation method, called the Buddy System, which guaranteed durability and increased availability of web services. In this paper we extend the Buddy System to enforce hierarchical data integrity constraints.