Not sure how to form the possessive of a plural? Can’t decide if the apostrophe goes before or after the S? Just do what this Yahoo! Celebrity writer did! Put it before and after the apostrophe:
Just in case the writer (or editor) is reading this, here’s the rule: To form the possessive of a singular name, add an apostrophe followed by an S. To form the possessive of a plural name, add an apostrophe after the S: Kardashians’.