I've just run into this exchange re Pope Eugenio Maria Pacelli.
Maybe I can help clarify his possible relation to you and the other people taking part in this discussion.
1st: There is no feminine for Pacelli, which is a family name and as such steady and invariable. If one's name is Pacella, he/she belongs to a different family.
2nd: Eugenio Pacelli was born in Rome from a noble Roman family, therefore any chance is rather remote for someone having been born in Salerno or anywhere else to be related to him.
Happy New Year!