5lbs is a very decent size for a preemie!
Love to all involved and congrats to you.
Re Great or Grand - stick with Great.
I was fonder of my Great Aunt Alice (now deceased, the only one of the five - how bad is my luck!) than I ever was of my Nan. See, we got around the Great bit there
This is what comes of having older sisters you see.
My niece might do it to my bro yet...