Most recent one I can think of is Billie Lourd getting a role in Star Wars because of her mother, Carrie Fisher. To be fair to them though, it was a very brief cameo, and she was brilliant on
Scream Queens so it's not as if she can't act, because she certainly can.
Chris Columbus' daughter, Eleanor, was the only American actress to appear in the first two
Harry Potter films. Again though, she has a cameo role, but he always conveniently placed her next to major characters at whatever chance he could get
And then there are the famous examples, like Jane Fonda and Jamie Lee Curtis, but they're both terrific actresses and worthy of the roles they receive.
But Jaden and Willow Smith would have never got anywhere close to where they are today had it not been for their parents
(*insert Jada's racist picture *)