It depends. How often do you see your aunt? How old is she? Are you on good terms? Would your dd be viewed as her namesake?
When I was pregnant with my first dd (
Kate), I discovered that my dh had a great aunt named
Katie. We already had the name picked out before we met her (before I even knew she existed) so imagine my surprise when we met. I was especially upset when my m-i-l told
Katie that we were naming our baby after her when I had never even heard of her! On top of that, dear old
Katie was a little odd. I briefly considered scraping the name but in the end decided that I'd probably never meet her again (we didn't) so why not keep the name I loved?
You're probably much closer to
Carolyn so only you can say. Personally, I'd say
Caroline and
Carolyn are different enough to be doable, especially if there's enough distance between the two.