How to use MySQL Server 5.6 for GeoIP replication?
Would you be interested in a MySQL Replication setup that is shaped like a snowflake ?

You could setup a Star Topology


Have a Write Master
Setup up a Distribution Master (DM). The role of the Distribution Master is simple


Slave to Write Master
Store No Data (All tables use BLACKHOLE Storage Engine)
Have Binary Logging Enabled
Act as Master to Multiple Read Slaves



For your case, you could have 

Write Master in WM1


DM1 as Slave to WM1


SLV1 as Slave to DM1
SLV2 as Slave to DM1

DM2 as Slave to WM1


SLV3 as Slave to DM2
SLV4 as Slave to DM2

DM3 as Slave to WM1


SLV5 as Slave to DM3
SLV6 as Slave to DM3



You could hang a DM as a Slave off of another DM

The possibilities are endless

I have written about setting this up before


https://stackoverflow.com/a/5781504/491757
https://serverfault.com/a/264444/69271
https://dba.stackexchange.com/a/9336/877