When two different voices on the same staff have overlapping note ranges, they get shifted and written side-by-side. For example:
What happens if there is an accidental on a note of the voice that was shifted to the right? For example, if the E in the first illustration is flat, or if the right B in the second illustration is flat. Does the accidental go between the two stems or to the left? If the latter, is there a way to disambiguate to which note the accidental applies (as in the second illustration)?
Sibelius always puts the accidentals to the left but it looks a little odd and can be ambiguous. What's a good reference for this?
EDIT: To clarify, this is a totally invented example. I have not seen this case happening, but one could notate it using a notation program. The question is whether there is an standard way to notate this, and the answer could totally be that there isn't.