I love
Kaylin! I think it works great with
Evan and
Alex.
Kinley would be okay with it too, but I think it sounds too masculine, and you definitely want something feminine.
For example if you just hear the names "
Alex and Kinley," you may not know which is a boy and which is a girl.
I would go with
Kaylin. I love it. And I love the mn
Elizabeth too! I like the spelling Kaelyn best.