Possessive of a word that's already possessive?
There is a famous pizza restaurant named "Domino's". In our city their rivals accept vouchers issued by Domino's. The sign reads "We accept all Domino's vouchers". Given that the name already has an apostrophe is this correct? Why not "We accept all Domino's' vouchers"?
Okay, I accept that perhaps that looks very strange but my point is that the registered name already has an apostrophe, does that now do the two jobs of being part of the name and indicating possession?