If, through one's learning, or through a family tradition, one has established a particular practice which flat-out rejects other practices, but then he is put in a situation where his traditional practice is impossible, can he be yotzei his obligation by following the practice he rejects?
For example, if one holds that horseradish is not an acceptable way of fulfilling the obligation to eat maror, but he is somewhere where it is the only option, can he be yotzei by eating horseradish because others have a tradition that it is a valid option? I am not talking about a case where there are a bunch of what one sees as valid traditions, but a case in which one rejects the validity of the practice he would be forced to rely on.
[note - I have two or three other potential parallel cases but there are other variables which make them not strictly parallel]
