Hello Mary,
congrats to your baby sister! I liked this project of yours cause it is just what all my relatives do when they want to prepare an "emotional text" of some sort or another, they ask me. My inspirational words are proudly occupying book title-pages, wishing cards and letters of love declaration (more or less everybody knows that I am hiding behind the aspiring author). Now, I always tell them, and I'm telling you for that matter, that it is best to write the thing yourself, however mundane and simple you think you find it, cause this way it's true and coming from the heart. And whatever comes from the heart is bound to move. However, I do understand your stress and uncertainty, so I propose that you cooperate with someone, let's say me, in order to produce a natural result, that is nonetheless "pleasant to the ear" and "literary correct". I can prepare you a random sample, so that you can see If you connect with my style of writing.
Have a nice day!