I have a site to site openvpn system

Installing and Using OpenWrt Network and Wireless Configuration
19

This diagram is confusing.
Try to follow the next example:

remote1---CentralSite---remote2

remote1 LAN is 192.168.11.0/24
remote2 LAN is 192.168.12.0/24
CentralSite LAN is 192.168.10.0/24

Server configuration:

push "route 192.168.10.0 255.255.255.0"
route 192.168.11.0 255.255.255.0
route 192.168.12.0 255.255.255.0

Then client-specific configuration files:
remote1:

iroute 192.168.11.0 255.255.255.0
push "route 192.168.12.0 255.255.255.0"

remote2:

iroute 192.168.12.0 255.255.255.0
push "route 192.168.11.0 255.255.255.0"

Not tested, but based on the live configuration.