Your daughter-in-law could possibly return to the Holy Faith after reading one or all of the following books:
The Wonder of Guadalupe, by Francis Johnston
Guadalupe, What Her Eyes Say, by Francis Anson
Not Made By Hands, The Miraculous Image of Our Lady of Guadalupe and The Holy Shroud of Turin, by Thomas Sennot
A Handbook On Guadalupe, Edited by Franciscan Friars of the Immaculate, Our Lady's Chapel, New Bedford, MA
Our Lady of Guadalupe and The Conquest of Darkness, by Warren H. Carroll
Another series of books, available from Tradition In Action which are excellent:
Our Lady of Good Success, Prophecies For Our Times, by Marian Therese Horvat, PhD
Stories and Miracles of Our Lady of Good Success, by Marian Therese Horvat, PhD
The Admirable Life of Mother Mariana, Volume I, by Fr. Manuel Sousa Pereira
The Admirable Life of Mother Mariana, Volume II, by Fr. Manuel Sousa Pereira
I do understand the predicament you're in, Cera. I, like you, am attempting to bring my beloved Paraguayan daughter-in-law back to the practice of our Holy Faith. May Our Good God grant it ....