They are seperate carriers. In the worst case, I will try winging it out. They are paper tkts.
I can try UA, but they misconnect to SQ flight to BOM, so I will have to overnite at SIN, which might be an issue as I am juggling for time at the moment

. And since I am changing carriers (UA instead of SQ) I will have to reissue the tkt then anyway.