Hi ,
I understand that out of four port per controller , you intend to connect three ports for direct connect to Host HBA
and the fourth port you will be connecting to a Ehternet switch , which in turn will connect to " Router " to connect to other site.
I do not see anything wrong in this setup and this should work. The management port of both the MSA need to be in the same network.
Regards
I am an HPE Employee