Do you mean something like this:
A is for adoption
B is for birthparents
H is for heart; you were born in ours.
J is for the joy we felt when your birthparents picked us.
L is for the love we have for you.
M is for the months we waited for you (here you could put photos of and write things that you did while waiting for the little one)
That kind of ABC's list? Those are just some things that came to the top of my head. Or is there an official alphabet that you're looking for? HTH, at any rate!