Re: Allow traffic from ssl-vpn to enter site to site tunnel on fortigate
Create an IP pool with an unused IP address in the LAN space that is allowed to transit the tunnel. In the SSL VPN policy that points to site B, enable NAT and use the IP address from the pool you just created. This will send all SSL VPN traffic to the remote subnet using the one IP address in the pool. Something to be aware from with this setup:
All traffic hitting any remote servers will share the MAC/IP address of the FGT interface/IP pool.
If that remote subnet has servers that you need compliance logging on, you won't have much success with that simple approach. At the end of the day, you will reach that subnet though.