Mysql database replication with offline servers

[Ashraful Islam]

I am just a developer, who doesn't have deep knowledge in DBA. So need experts suggestions in this. I have two offline databases in two cities, I want to make a synchronization between two databases using a third database which will be stay alway online in a live server.

My problem is like this, Location A database is in New York. Location B database is in Canada. And they are in local machine, so no connection between them. Now I need to show the changes of Location A's to Location B and Location B's to Location A. Yeah this can be solve by MASTER-MASTER replication. Also i have found a way to solve autoincrement indexes issue, by separating index numbers in different servers.

But I need another live server C where Location A's and Location B's change will reflect. So some users need not to access Location A or Location B for looking into changes. I do not also want's to use RING replication. because if one goes down then rest of the RING will be broken.

In summery I want to make the replication like this

https://goo.gl/HmQyzo

Need help about replication process.

Thanks in advance,

Nixon