Hello all..........I am trying to create a multi-site failover cluster (Sql Server 2012).  Due to some support issues, I am unable to use AOAG, so I have decided to use Mirroring among two-2 locations with each

location holding separates instances.  Consider following:
There is Location A and B.
There are two-2 servers each in Location A and B.  They have their own storage.
Location A already has two-2 node failover cluster.  It has instance named Instance_A.

We need to introduce two-2 nodes from Location B to the failover cluster in Location A with its separate instance named Instance_B? How can I make it work?

If I go ahead with the setup.exe from SQL media and try to add node, it will ask me to choose the instance and the only instance available would be Instance_A, but I do not want it to connect to Instance_A.  I

want to join the two-2 nodes in Location B to the failover cluster in a way that Instance_B stays on Location B servers and Instance_A stays on Location A servers.  So that I can configure mirroring among the two.  I would appreciate headway into this.  Thanks.