There is no more a rule for the processional, so you are happy to customize it at your own pleasure depending your faith and culture.
The officiant walks first followed by the groom, groom’s grandfathers, bride’s grandfathers, groom’s family and the mother of the groom usually accompanied by one of the usher, brother or close relative. The bride as tradition will walk with her father.
We suggest two different music for the processional: once for all the family and one for the bride.
The recessional is the same just reversing the order: bride and groom go first followed by best men and bridesmaids together and last the families.
Italian weddings are culturally very simple on processional: the groom waits at the altar, there are no bridesmaids or best men, two or four witnesses wait on the side of the groom, sometimes there is a flower girl and the bride walks the isle with her father.