A system, method, and computer readable medium for control and synchronization of data between collaborative database systems. These databases are not exact duplicates and in face involve locally private data. The data is shared at the discretion of a local database and can happen during times of low system or communication demand. The use of merging a particular text string into one of the database fields after data is sent between systems is used to tag the synchronization. No time stamps or similar dating is used. This enables no addition to the data fields that are in use between the database. Care is taken to assure timely and correct synchronization while not sending data that has already been sent.