Maybe our surname comes from the latin "magnii" as plural of "magno". Who knows?
My grandfather was bornin 1899 or 1900 (I don´t remember exactly). He came to Argentina before 1907. His name was Tobías Angel MAGNI. His father´s name was Paolo (known as "Pablo" in spanish). Unfortunately I couldn´t see him alive because he died in the 30´. If you can add more information both origins or the genealogic tree I´ll be very grateful