Thanks for the tips.
I have recently now taken over the province just north east of Napoli. I offered the Count there vassalisation and after several rebuffs he at last accepted. Now the Principality of Campania consists of three provinces and I'm as happy as Larry .

All the rest of southern Italy belongs to a Duke. Only two of his seven or so provinces look useful militarily. Napoli itself is very strong in this department and I'm considering an armed invasion.

BTW, my Count's wife is daughter to the great Alexius Komnenus. That guy has some unbelieveable stats!