I would use the second. The first is equally grammatical. It's a matter of personal choice for most people. I was interested to discover, when I tutored a 6-year-old Spanish boy, that his textbooks listed "have got" as the verb for possession, rather than "have". I always taught my adult students that both were possible and acceptable.
The fact that your example was about a relative makes no difference to my opinion. I would be the same if we were talking about a pen or a dog or a hat.