CathInfo.com

I wonder if the switch from the true Sr. Lucy to the false Sr. Lucy was done in the following manner.  The real one is removed at some point in time from the monastery at Coimbra and the remaining nuns are informed that she was transferred to another monastery of the Order of Discalced Carmelites, but perhaps they are not informed which one.  In any events any attempts by the nuns to communicate via letters with her are thwarted by having their communications go unanswered or answered by some false 3rd party.  Or the letters could be answered for a period of time by the real Sr. Lucy, but only for a certain period of time until they are no longer answered or answered by a  false
3rd party 

Then during a period of transition which could have been some years all the remaining nuns at Coimbra die off or are transferred to other O.C.D. monasteries and replaced by other nuns who have never had a face to face encounter with Sr. Lucy and have never seen any recent photos of her.  Eventually, all the remaining nuns are replaced and once that is done the fake Sr. Lucy "returns" to the monastery in Coimbra.  That scenario would obviously be planned so as to not have the return of the fake Sr. Lucy raise any suspicions with the "replacement" nuns.