Gunner
There a few issues here mate, most of which relate to the initial booking.
1/. An SSR requesting meet and assist should have been loaded into the system at the time of booking. This will alert the ground handlers (Rat or otherwise) that there is a special needs PSGR inbound. Obviously the DBML was loaded correctly, so that is good. The correct format is MAAS, and loading an OTHS SSR or an OSI SQ CKIN will not push the right buttons and immediately cause an oversight of the special needs.
2/. Passengers travelling with sharps (ie: the necessary hypodermics to keep Mum well) need to carry a copy of the prescription. This is SOP, and if the correct information is not relayed to the airline at the correct time the whole thing is bound to go pear shaped. Simple as that, but without some rule waiving she could have been legitimately denied boarding.
3/. A call should have been made to SQ Sales requesting access to the J Class/PPS counter. In my experience, SQ are very accommodating.
4/. Immediate contact with their sales desk at the airport would have found the SQ Airport duty manager and short circuited the process nicely.
If the system is to work properly for you Gunner, then the groundwork needs to be done with some care in advance.
I would very much like to inspect the PNR to see what was loaded and what wasnt, and to know where it was booked.
You were not advised at point of sale of some very important procedural information.
Generally we have little or no problems with special needs passengers, because they are fully armed with the correct information before they hit the airport.
I wouldn't go shooting Rat checkin just yet, even though they may have been able to go an extra yard or so.
Best regards
EWL