OP - It is really hard to help people who will not supply the actual details of their itinerary. Without that, all you get is theory. Instead of A, B and C, please provide the specific cities and flights.

People here are often have helpful and practical solutions to seemingly tough problems once they learn what A,B, and C really are.

For others, while the general rule is that it is the responsibility of the late delivering carrier to rebook in the event of a misconnect and that is true for all tickets, cash & awards, the inconvenience always falls on the passenger.

Booking a 37 minute connection D-I for the last flight of the day where the onward flight is apparently to Japan may be within the MCT but is rarely within the SCT (Sensible Connect Time). The best time to deal with these issues is not just before travel, but before booking.

Not every itinerary has convenient connections, but whatever those connections are, they do not get better.