I'm being godmother to an 11 year old girl, i feel hugely honoured & touched that she has asked me to be a part of her life. I'm sitting here with the card & can't find any suitable words to write, I'm in need of some inspiration.
Since she has asked for you herself (from what you say) rather than you being asked by the parents, as in the case of a baby, I would write to her directly, saying how pleased you are to be asked to take on this role, and telling her that you will always be part of her life and that you'll be there for her whenever she needs you. I don't know if you're already related, but if you are not, you could tell her that it'll be like her getting a new member of her extended family (and you yours).
You could tell her that you will take the promises that you'll make seriously, and that you will help her to keep the promised that she will make.
Umm... I do tend to the verbose ... but is any of this helping?
Thank you, i've managed to write a few words. she is a very special young girl & i know we will both be very teary, she is my husbands cousins daughter but we are close & i am very honoured that she chose me herself. Tissues at the ready i think x