Part of the "creed of the FCOM" is that not all situations are considered, and that compound emergencies are not addressed. Unless there is a specific procedure for "Fire on single operative engine", the 'Captain must use best judgement' clause takes precedence:
The flight crew must be aware that checklists cannot be created for all conceivable situations and are not intended to replace good judgment. In some situations, at the captain’s discretion, deviation from a checklist may be needed.
However, that's the Boeing "creed"; Airbus may have a different one...