http://www.bahai.org/library/authoritative-texts/the-universal-house-of-justice/messages/19631006_001/19631006_001.pdf
There is no way to appoint.. a second Guardian to succeed Shoghi Effendi.
http://www.bahai.org/library/authoritative-texts/the-universal-house-of-justice/messages/19631006_001/19631006_001.pdf