No mixing in SIN? Not in your experience? Which terminal are you talking about. I haven't been there since September but departures and arrivals are all on the same level with inbound AND outbound pax all mixing together. They have individual screening on each gate so they don't give a stuff who gives what to whom as they screen you before you board. If you want to meet the inbound crew you just need to wait at the exit of the gate they arrived on. We used to do handover briefs all the time. In fact, it wasn't unusual if the inbound a/c was late to actually do the handover on the aerobridge.