Jean Luc Robin had supposedly said in his book that Philippe de Chèrisey had admitted to him that he had made up the parchments. Here is the piece in Robin's book where he says he admitted it:
"When I returned to Rennes-les-Bains in 1961 and learned that, following the death of the Abbé, the Marie of Rennes-le-Chateau had burned down (along with all its archives), I took advantage of the opportunity to invent the story that the Mayor had an exact copy made of the Parchments that the Abbé had discovered. And so, at the suggestion of Francis Blanche, I set myself the task of making a copy employing a code based on some passages from the Gospels, and then decoding what I had just encoded. Finally, by a roundabout route, I delivered the fruits of my labours to Gerard de Sède. This document has had a life of its own beyond my wildest dreams."
Quoted from Jean Luc Robin's "La Colline Envoutee" (Guy Tredaniel, 1982)
De Cherisey said here: i set myself the task of making a copy employing a code based on some passages from the Gospels, and then decoding what I had just encoded." But HE MADE A COPY. A COPY OF WHAT? AN ORIGINAL? Notice he didn't say he made a new parchment, implying here that there were genuine documents and he knew about them.
This whole scenario seems to have some basis in fact as reported by René Descadeillas (1909-1986), who had been Curator of the Carcassonne Library and Director of the Museum of Fine Arts in Carcassonne. He wrote;
'the repairs concern, among others, the high altar. The church of Rennes, & its actual buildings seem very old if we believe a report of the diocesan architect M. Cals, Carcassonne (Arch Aude, O-Rennes series) *. It had a primitive altar, made of a stone table supported in front by two square pillars, one of which bore archaic sculptures *. It appears - several witnesses still exist, and they are adamant - when loosening the entablature, one of them discovered a cavity filled with dry ferns, in the middle of which one could distinguish two or three rollers. It was parchments which the priest seized. He [the priest] stated - it is a witness who tells us - that Saunière read them and said he would translate them if he could . The mayor, informed of the fact, asked the parish priest for the translation; Sauniere confided to him shortly after a written translation in his own hand. The translated text related, it seems, to the construction of the church and the altar. We do not know what has become of the document.
Cherisey writes 'I set myself the task of making a copy employing a code based on some passages from the Gospels ....'
So he knows about a parchment being found and Cherisey set himself the task of copying it, but adding a code .... this is what the authors Andrews & Schellenberger had deduced by a very different route!