bi-directional sync of mysql databases

hi :) i am looking for someone to create a script to do the following we have 2 databases one for company A and one for company B both comanys A and B uses the same script and the version of the script is the same also we would like a script that would bi-directional sync with a master please see image whilst i explain the next part i would copy company A database to the master DB for this but there are rows in company B that i can not have sync at all. this must have the following [login to view URL] to set up for us as we will not give details to our databases 2. able to add rows to the not include sync with ease 3 easy written text with set up and editing needs but this must be set up so if database 2 updates it updates the others automatically in real time and the other way round i have been told this is a simple task so i do not want to spend a lot of money on this so your bid will make a difference to who we assign this project to. one last thing!!!! MUST BE SECURE! thanks