Hope this helps, not exactly your scenario but I think it should help

I flew AKL-SIN (on an NZ ticket and NZ plane) arriving at 6:45am into SIN and was flying onto PEN the following day at 7pm (on a separate SQ ticket).
NZ in AKL were happy to check me straight through to PEN but I had 3pcs of baggage and only wanted 2 to PEN.

The supervisor said they could check all bags through to PEN from AKL (even on separate tickets) OR check only to SIN and I'd have to recheck, wasn't able to split or short check the bags.

I assume you're wanting to come out of the airport anyway and SQ were happy to check in for me up to 48h before the SQ flight, so while not as convenient you can still offload your bags as a worse case.
Reference (https://www.singaporeair.com/en_UK/s...port-check-in/)