checking in baggage on 2 tickets
I have SFO-SIN roundtrip on UA purchased through UA. I have a SIN-BOM roundtrip on SQ purchased through SQ. The flight segments connect SFO-BOM and BOM-SFO with approximately an hour+ layover in SIN. I had to do this because UA would not allow me to purchase the SFO-BOM ticket with $, although it sold me the same SFO-SIN-BOM flights for my mother on miles. (I did not have miles to buy both tickets). My question is if I will be able to checkin my baggage at SFO all the way to BOM and do the same when returning, checkin at BOM all the way to SFO. I will have UA Premier Platinum status when I make the trip if it matters. Many thanks.