FileServer and MySQL replication among multiple "independent" sites with unstable WAN

I need an engineer with lots of experience in setting up complicated MySQL Replication networks. The scope of this project is to setup (and test) the FileServers and MySQL Servers in 2 centers such that the below requirements are met. Context ------------- Currently I have 1 server in 1 medical center, and all clients read/write on the MySQL and Fileserver on that server. The new setup will have 2 centers (more centers later). Assume that the connection between the centers is very unstable (this is in Africa). Requirements ----------------------- The requirements are the following: 1- Each center should be able to run on its own (even when there is no connection to other centers - This means that the clients in center 1 should be able to read/write in the MySQL DB of center 1, and the clients of center 2 should be able to read/write in the MySQL DB of center 2) 2- All the data should be replicated in all the centers so that a patient can go to any center 3- If the same patient goes to center 1 (some read/writes done in center 1), and then goes to center 2 (some read/writes done in center 2) while there is no connection between the two centers, the data should still sync without any conflicts. Notes ---------- - Ideally, there should be no modification needed in the client applications. - Before awarding you the project, I will challenge you on your design to make sure that you understood all the requirements (especially #3). When placing your bid, you need to explain your design so that I can challenge it. - If I see that you perform really well on this task, I may hire you on a more regular basis as my database manager (and if you know how to code, in PHP/jQuery then I may ask you to join the programming team too) Thank you!