I wanted to include this possible variation separately as it is most unlike the others.and possibly needs more information before confirmation.
Vidachevich, referring to Marco listed as resident and recipient of privileges at Drvenik, Makarska in:
Bartulovich, Pietro, 1775, Chronicon della dedizione e privilegio di Macarsca, Primorie e Craina, in ugualita de Pastrovichio dalla Maesta Veneta, conceduto e confernato (available online)
One thing that lends credibility to Vidachevich being a corruption of Vitasović is the large land holdings of Vitasović in Drvenik before the Nation alisation of approx 50 hectares. I would be interested in thoughts on this.