A method may include maintaining first data structure with records organized in a first hierarchy, and maintaining a second data structure with records organized in a second hierarchy. The method may also include receiving a first change request for a value stored in a first record. The first change request may be received from a parent in the first data structure of the first record. The method may additionally include changing the first value according to the first change request, and receiving a second change request for the value stored in the first record. The second change request may be received from a parent in the second data structure of the first record. The method may further include sending a notification to the parent in the first data structure that the parent in the second data structure is attempting to change the first record.