Combining two different subnet into one subnet

wakson005

Let say I have two different subnet due to openvpn requirement.

Site 1:
Subnet: 192.168.1.0/24

Site 2:
Subnet: 192.168.2.0/24

Site 1 & 2 has VPN connection so they can communicate with each other fine. Issue is multiple HA clients due to HA needs a single subnet for its connection and I need to specify this subnet but obviously if i specify subnet for clients there will be the following issue:

Ping between 192.168.1.11 & 192.168.2.12 works
Site 1:
client 1:
IP: 192.168.1.11
Subnet: 192.168.1.0/24

Site 2:
client 2:
IP: 192.168.2.12
Subnet: 192.168.2.0/24

Issue is subnet is different so when enter it claim these two clients are on different subnet and shouldn't be connected together even though all communication is working through VPN tunnel. Is it possible to create a supersubnet with the two locally to translate a supersubnet 192.168.8.0/23 to 192.168.1.0/24
& 192.168.2.0/24.

Example
192.168.8.0/23 such that
192.168.8.0-192.168.8.255 in it translated to ->192.168.1.0/24
192.168.9.0-192.168.9.255 in it translated to ->192.168.2.0/24