your adjustment cleared up some doubts on the family name but still I find it very unusual that they stated on a Marriage Act "D'Incerto padre" which means "of uncertain father".
I can imagine two circumstances which might lead to "uncertain father" -
a) an infant or toddler child is left orphaned by some catastrophe or perhaps war. The child is taken in and raised by another family or orphanage, but no one knows his/her parentage.
b) an unwed mother gives birth to a child and either refuses to name the father or cannot name the father with certainty (if the mother were a known prostitute, for example).
Hey, just a couple of guesses...