EC 3749 then IB 5150 at Barcelona
Milan → Barcelona → Seville
Timetable, Barcelona time
21:30EC 3749 from Milan at the gate
15:45IB 5150 to Seville leaves the gate
18 h 15 apart on the timetable, overnight
IB 5150 leaves 18 h 15 after EC 3749 arrives on the timetable: more than half a day, so not a connection we count.