Need to configure Availability Groups between three different SQL failover instance We have total 6 Nodes and 3 failover cluster (Each with two node).


Cluster1.TestAD.com(Node1,Node2) - SQL Failover Instance (SQL1) - 1
TB Shared storage
Cluster2.TestAD.com(Node3,Node4) - SQL Failover
Instance (SQL2)- 1 TB Shared storage 
Cluster3.TestAD.com(Node5,Node6) - SQL Failover Instance (SQL3)- 1 TB Shared storage


Now we want to create availability group setup between above three SQL instance.

We plan to create new cluster (cluster4.TestAD.com ) with all six node and create Availability groups with all three instance. 

SQL Edition : SQL Server 2012 R2 Enterprise

Is it possible? Any other recommendations ?
One of the requirements for AGs is that all instances are participating nodes in the same WSFC.  I believe, based on what youa re telling us, is that the 3 instances are, in fact, in 3 separate clusters.

I don't believe that what you are trying to accomplish is possible.