If you mean "can a member of my family have their name added to the electoral register without the house owner knowing?" then the answer is yes. Everybody on the electoral register has the option of having his/her name only available to candidates and other election workers, rather than on the main register which is publicly available. If you meant something different, then I don't know.
What happens if you don't complete your details on the electorate roll? I had a letter recently telling me it was illegal to not fill in a form and send it back to my local council.