I have accidentally removed the FarmAdmin account from the WSS_WPG group on our MOSS2010 server. Earlier it was part of WSS_ADMIN_WPG and WSS_WPG groups. Now it's only WSS_ADMIN_WPG.
In User Accounts on the server, I cannot add him to multiple groups. I can however add him to administrators, but I'd prefer not to.
How can I reset the FarmAdmin account group memberships on the MOSS2010 server?