HA Configuration (One in primary and One in DR)

Hi folks, 
  I currently  have HA pair (active/passive) in a primary data center and we are bringing up a DR.

wondering can I split up the HA pair (One in primary and One in DR) and continue to have HA with utilizing different subnets? We are using multiple IPSEC tunnels to connect the sites so we are still working on whether  we can extend subnets but if we can't I wanted to ask if different subnets are possible.

Thank you any info is appreciated