Employers in the US learned the Family Medical Leave Act protects an employee’s job rights even if the employee fails to indicate an expected return-to-work date. Not only that, but the same decision declared a grandchild qualifies for consideration even if the employee isn’t a guardian.
The case is Gienapp vs Harbor Crest, decided by the 7th Circuit US Court of Appeals, and it is sure to produce waves across the country.  Here is a brief article describing the June 24, 2014 decision.