KL 618 then HV 6867 at Schiphol
Boston → Amsterdam → Athens
Timetable, Amsterdam time
09:45KL 618 from Boston at the gate
07:00HV 6867 to Athens leaves the gate
21 h 15 apart on the timetable, overnight
HV 6867 leaves 21 h 15 after KL 618 arrives on the timetable: more than half a day, so not a connection we count.