• Jeff -

    There is no way to specify a named instance with the SET PARTNER = xxx, but you are able to use an alternate TCP port.

    Each SQL Server instance should use a different port for database mirroring.

    serverA 192.168.1.4:5022

    serverA/instance1 192.168.1.4:5023

    serverA/instance2 192.168.1.4:5024

    Hope that helps!

    Mike