Well, i just saw your message in the "Name Issues" thread on the forum, so i came talk to you here so the talk there doesn't go out of topic.
Could you try to register for me, please ? Now that you said about the stay logged option I believe it would be easier for me to help here.
I wonder if its possible to create one with my email (firstname.lastname@example.org). If it doesn't work its because friend used it in another wikia. I don't really know if the same email can be used in different wikias, as the wikia community help pages aren't that expecific. If it can't, a help with one of your unused emails would be greatly appreciated.