So, how many apostrophes are OK?
Any number: "Sarah’s daughter’s boyfriend’s mother's
dog's food" is fine. 18 (43%)
Three is the limit: "Sarah’s daughter’s boyfriend’s mother"
is fine. 3 (7%)
Two: "Sarah’s daughter’s boyfriend" is fine. 19 (46%)
One: "Sarah's daughter." 1 (2%)
I tend to agree with two; otherwise, it becomes way too cumbersome. If you want to indicate possessives of possessives, you could use of: "the mother of Sarah's daughter's boyfriend," but I still think that's cumbersome. Perhaps I should revise my opinion to one only.
I'm surprised that some of you would allow any number!