DrayTek 2860 - 2830 double vpn not passing traffic

Hello

I have a system whereby two separate LAN-LAN VPNs connect to the head office, all using DrayTek routers. The VPNs work fine, but I need each remote site to be able to contact the other. I have added the remote subnets to each LAN and they appear in the routing tables, but I cannot ping one remote office from the other.

Do I need to adjust the subnets on each VPN or something else?

I left the subnets as they were and made sure that the tick box to have a separate phase II for each subnet was not ticked and it suddenly sprung to life...??