If each database has a serial number ID starting at 001 and incrementing by 1 and a relationship between the two is created based on that ID. When database A has a new contact created with serial number 005, and the name is entered, then if database B has a new record created with the same ID number, AND it contains related fields for the database A name field, the data will magically appear.
This is the simplest way to sychronize the two databases. There are 6 or 7 other ways, mostly involving scripts and or timed events.
The Computer Guy, Seattle