Answer:
Words with apostrophes are treated differently in word processing than in directories.
Directories will sort by following words or fields, ignoring the apostrophe.
Sisters' Restaurant
Sister's Sewing
Sisters Tavern
Word processors follow a different logic. The first entry will always be one without an apostrophe, followed by entries based on the first occurrence of the apostrophe :
Sisters
Sis'ters
Sister's
Sisters'