no there isn't. the point of the question is to see if you can rationally think on your feet. for example, the old proven procedure vs new experimental procedure with better results, i said i'd go for the new experimental treatment (provided there are no contraindications) because i want to give my patient the best shot they have. of course, this depends on how much better the new is over the old. you can argue it the other way; the old procedure is a sure bet while you feel the new stuff carries too many risks.
adcoms as these questions not to grill you and make you pee your pants. they're probing your brain and seeing how you think.
i'd agree with you on the parents and child since the child is your patient. on the actual patient refusing, i'd inform them of the risks of not receiving the transfusion i.e. death or debilitation, and strongly urge them to take the transfusion. in the end, they have the right to deny medical treatment, just as there are DNR orders (another grey area). shrugs, we can discuss this more; i just don't see a compelling reason to force a patient to receive a transfusion when he/she is well informed.