I am so ecstatic that you have become a member of my family. May your birthday bring to you all the wonderful things that you have ever wished for in life. Happy birthday!
Sister-in-Law, I would hope that on your special day you are surrounded by love. But there really is no need to hope, because I will be there, so it’s a given. I love you, not just because you are family, but because you are a remarkable person who I am glad to call my friend.
If you drop the in-law part of sister-in-law, then you will have what I really consider you to be: a sister. I am so grateful that I am blessed with another sister in my life, and I hope you can consider me to be your sister as well. May your special day be full of luck, laughter, and love.
Since I have such a large family, I have no shortage of in-laws. But the one in-law that I can always turn to for advice, support, and love is you. I am so glad that you are a part of my life, and I hope that your big day is full of cheerful people, cool presents, and chocolate cake.
My brother has done a lot of stupid, crazy things in his life, but marrying you was not one of them. In fact, it might be the only smart thing he has ever done! Thank you for becoming a part of our family, and may you have an enjoyable birthday full to the brim with hope and delight.