I'm sorry I'm a bit late but - Thank you for bringing back memories of that feeling.
I'm way behind you, only having three.
There's something about a daughter producing a child that is unexplainable. You sound as though you were able to be with her. What a privilege!
You think that you can never love anything more than you love your own children and then you find out you can! Theirs!
Give her a cuddle from me and whisper in her ear how much you love her.
P.S. Look at my sign-on name. I was named this by my first granddaughter and I carry it proudly