VATICAN CITY — The rite of canonization for Blesseds John XXIII and John Paul II April 27 will use the standard formula for the creation of new saints, but the Mass will be preceded by the recitation of the Divine Mercy chaplet, and it is possible retired Pope Benedict XVI will attend, the Vatican spokesman said.Pope John Paul II embraces Argentine Cardinal Jorge Bergoglio after presenting the new cardinal with a red beretta at the Vatican Feb. 21, 2001. It was the Polish pontiff’s choice of cardinals that would help set the stage for the eventual election of Cardinal Bergoglio (Pope Francis) following the resignation of Pope Benedict XVI. (CNS photo/Reuters)

“He is invited,” said Jesuit Fr. Federico Lombardi, the spokesman. “But there is still a month to go. We’ll have to see if he wants to be present and feels up to it.”

Discussing preparations for the canonizations with reporters March 31, Fr. Lombardi said the popes’ tombs in St. Peter’s Basilica would not be disturbed, other than to change the inscriptions from “blessed” to “saint.” Pilgrims can visit them after the April 27 Mass.

Relics from the two popes will be presented during the liturgy, the spokesman said. The relic of Blessed John Paul – a vial of his blood encased in a reliquary featuring a silver sculpture of olive branches – will be the same that was used for his beatification in 2011.

A matching reliquary has been made for a relic of Blessed John, said Msgr. Guilo Dellavite, an official of the Diocese of Bergamo, where the pope was born. When Blessed John was beatified in 2000, no relic was presented, the monsignor said, because no blood or body parts had been preserved for that purpose. However, when Blessed John’s tomb was opened in 2001 and the remains treated before being reinterred in St. Peter’s Basilica, some bone fragments were removed.

The canonization Mass is scheduled to begin at 10 a.m. the Sunday after Easter, which the church celebrates as Divine Mercy Sunday. Pilgrims are expected to begin filling St. Peter’s Square early in the morning, Fr. Lombardi said, and will have an opportunity to participate in the recitation of the Divine Mercy chaplet.

The Vatican, he said, is not issuing tickets for the Mass, although large sections of St. Peter’s Square will be reserved for official government delegations, for bishops and priests, and for members of the Vatican diplomatic corps. Other than that, space in the square will be allotted on a first-come, first-served basis

“If people filled St. Peter’s Square and (the main boulevard) back to the Tiber River, we calculate there would be between 200,000 and 250,000 people,” Fr. Lombardi said. Forecasts, including by city of Rome officials, that mention millions of pilgrims trying to attend the event appear exaggerated, he said.

“Come to Rome. Don’t be afraid,” he said.

Cardinal Agostino Vallini, papal vicar for Rome, told reporters that the diocese was focusing on a spiritual preparation for the canonization of “two pontiffs, two bishops of Rome, who lived and experienced their faith, becoming messengers of the Gospel, but also of great humanity.”

The cardinal will lead an evening for young people April 22 along with the postulators – official promoters – of the sainthood causes of the two popes. The night before the canonization, 11 churches near the Vatican will be open all night for prayer, meditation and confessions. The program will be offered in English and Italian at the Basilica of St. Mark the Evangelist at the Campidoglio and in Italian and Spanish at the Jesuit Church of the Gesu.