I've done a search, but think my question is probably a little too specific, so I'll throw it open to anyone who is prepared to offer advice.

I have an upcoming trip with my father MEL-SIN RT on BA, and we're planning to add a SIN-HKG RT on CX. These would be two separate bookings, both in the Y cabin.

We're looking at connecting the HKG-SIN leg with SIN-MEL, and the flights that appeal have a 1hr 45min connection. The next best option is around 5hrs, which is less than desirable. I'm QF Gold (OW Sapphire), so we have lounge access to pass the time if need be.

I'm thinking 1hr 45min at SIN is a relatively safe connection, as both us and the bags will be checked through from HKG to MEL, but I'm just a little nervous that 1:45 is cutting it fine. At the end of a trip, the last thing I want is the stress of missing a flight. And should the CX flight be delayed and we miss our BA flight, are BA obliged to put us on the next flight?

Anyone care to offer their advice or suggest what they would do in this situation?

Cheers.