Thanks. We actually wanted some specific FBA users to manage the management pages without them being site collection admins.
Also, when try to add fba user to site collection administrators list in site setting and it does not resolve the name.
However we tested this out on one of the 2007 portals. I can add my test FBA account to the Owners group which has Full Control permissions on the site and after that, I can go to Manage Users under Users and Permissions
and add, edit, delete FBA accounts.
is it not the same in 2010?