I would like to setup access for SBS2008 remote VPN users to adjacent gateway VPN subnets in the office.

For instance -
User connects to site A using pptp to SBS2008 box. This box is on a subnet that has a gateway VPN to an adjacent site B setup by 2 WG834G routers.

The user would like access to the resources on site B through the remote PPTP VPN.

I have enabled RIP2 on all the routers but still cannot connect to machines on the site B.

Is there something I am missing here?

This is the result I am hoping to achieve.