DL 173 - JFK-NRT diverted to DTW on 6/30 - need advice
When you book a separate ticket on another airline, you got to give yourself some leeway for delays/problems with your flights on your separate ticket. They will throw some compensation miles or ECVs but not responsible for more than that.
"They were scheduled to arrive in BKK around 11pm and have a 630am booked on Bangkok Airways to USM (separate ticket)."