You want one login to view all? I requested it the last time. It is easy I think.
Here is what you should do:
1. Login to one account which has your other domain.
2. Then when you have logged in, you notice there are fields under, "Change Login".
3. Change the Username and Password to that of your main account and submit changes.
4. Do the same for your other domains.
5. You should be able to login now to your main account with all the domains viewable.
I hope that helps.
EDIT: By the way, if you forgot your password for one domain, you can always request it in the Account Login section.