For multiple accounts, set up the one you want the router to connect to like the 1st pic I posted. That's pvc 0 under wan.
Then set up pvc 1 like this pic:
You will then have the modem maintaining a connection with the account embedded on it, and you will have "dial-up" pppoe enabled (bridge mode) as well, so you can make a pppoe connection from windows. Ensure you keep clicking on save settings and then always going to "save & reboot" with each config change.
Herewith someone else's explanation that I saved long ago:
"In short, our default connection is routed by the Marconi, and I can dial a second PPPoE connection from any PC on the network.
Just in case anyone is wondering the setup is as follows now:
Pvc0
Virtual Circuit - Enabled
Bridge - Enabled (!!!! Without this, it seems you cannot dial a PPPoE connection from a PC)
IGMP - Disabled
Encapsulation - PPPoE LLC
Username and password of default account entered.
Pvc1
Virtual Circuit - Enabled
Bridge - Enabled
IGMP - Disabled
Encapsulation - 1483 Bridged IP LLC
Username and password left blank"
Hope you come right...
edit: I see this was discussed four years ago...
http://mybroadband.co.za/vb/archive/index.php/t-48772.html