Some business names appear in possessive form, such as “McDonald’s” and “Wendy’s.” So … how do we make a possessive of such nouns that already appear in possessive form?
Technical writing rules for such things would suggest adding yet another apostrophe-s to the word, e.g., “You should try McDonald’s’s new succotash milkshake!”
Yikes! Although defensible according to standard rules, such a bizarre spelling would probably shock and repulse your reader even more than the notion of milkshake tasting of lima beans and corn. Fortunately, there are better alternatives.
One solution is to avoid the problem by rephrasing, e.g., “You should try the new succotash milkshake at McDonald’s!” And it is also perfectly acceptable to allow the company’s name to function as a kind of possessive, e.g., “McDonald’s succotash milkshake is my favorite!” Either alternative is more pleasing (and tastier) to your reader than a McDonald’s’s succotash milkshake!
That is all for now …