You have 'brother-ships' in Greece?
of course saltydog
..a few examples are:
Blue Star Paros-Blue Star Naxos (there's also Blue Star Ithaki which has fewer cabins than the others)
Blue Star 1-Blue Star 2
Blue Star Patmos-Blue Star Delos (there are only a few differences between them)
Nissos Chios-Nissos Mykonos (there are only a few differences between them)
Olympic Champion-Hellenic Spirit
Speedrunner III-Speedrunner IV
Knossos Palace-Festos Palace-Olympia Palace-Europa Palace