I don't really love
Kerry as a fn for a little girl, but I think it's ok, especially since its honoring. I like the idea of honoring your aunt, but the spelling reminds me of a surname (
John Kerry).
Using it as a middle name is a nice idea, or maybe you could use a first name that
Kerry could be a nickname for. The only one that comes to mind is a "made up name" Keribeth. I've heard of Meribeth before, so I suppose Keribeth might not be too much of a strength, although I don't know if it fits with your other names or not.
As RoxStar mentioned too, I think using
Carrie would be a nice way to honor your aunt - even if the spelling isn't the same, it's the same name, and as long as she knew you were using Carrie/Caroline to honor her, I think it would be nice.