Pregnant or nursing person with credible temporary risk: a concession now, make-up later, no additional fidyah under the stated Hanafi rule.
Very elderly person with lasting inability: fasting may be omitted, with a prescribed daily food allowance.
Person dies owing make-up fasts after making an effective bequest: establish the outstanding days, then arrange feeding in accordance with bequest and estate rules. The diagnosis of the case comes before its legal outcome.