adding subnets to a current network

I have a current network in one location with 6 servers and 40 workstations accessing ( and being accessed from) the internet via dual
DSL circuits through a dlink RV042 dual Wan balanced router.(Working fine)
The local network is 192.168.1.1/24

I need to add three remote sites via VPN subnets. I have one site set up and connected via another dsl circuit to a local pc . the remote site
is 192.168.1.1/25 and the local pc is 192.168.1.129/25 .
Works fine and i can connect to network drives and printer on the remote site.
My next problem is to integrate this into the main network without disturbing too much. What I am thinking is to rename the subnets on the VPN as 192.168.2.0/23 etc and bring them into a dual nicc'ed pc with
192.168.2.0/23 and 192.168.1.0/23 on the nic's. and then change
the main local network to /23 . IS this the best way to do it ?
Or is there a better way. My problem is that to change the remote site to 192.168.2.0 means redoing the local speedstream 6520/ Linksys RVS4000 on site ( a pain) as once is change one I can't change the other !.
Thanks in advance.