I have 2 adopted sons, please just say 'for___' or 'made with love for___', or not anything written at all. The hearts are a nice idea. If you have people just sign their name in the hearts, I think that is very nice. Not everyone will know what to say, and a signature is easy. It is not necessary to draw attention to the 'adopted' part. Believe me, she is well aware of the fact. My congratulations to the whole family.