DAC Mode in a DAG

Hi

I have two Mailbox servers in the Primary Data Center. I have another two mailboxes in a DR site. I want to add the two DR Mailboxes to the DAG that already contains Mailbox 1 and 2 in the primary site. So now all 4 servers are in the same stretched DAG.

My question now is, if i want to prevent brain split syndrome by activating DAC on the DAG, will i still have automatic failover from Mailbox 1 to 2 in the primary data center?

In other words I only want automatic fail over from mailbox 1 to 2  in the primary and manually switch over to Mail box 4 and 5 in DR. Is this possible if DAC is activated on this DAG?

Thanks