Dear [name of Brother-in-law],
I wanted a brother but god gifted me with my little sister who made me laugh and cry for everything. Now, she has chosen the most beautiful life-partner in you, I am blessed with the dream brother that I longed for. The award for tolerating my sister for these many years goes to my lovely brother-in-law. Though both of you annoy me at times still you have been my best buddy in life, my best friend, my biggest support and angels of my life. You look the happiest with my sister. The way your eyes gleam by a meagre glance of his is bliss to watch. You both are match made in paradise, an embodiment of perfection when together. I want this excellence to stay till infinity.
The secret of a happy marriage is finding the right person and staying in love with them all the time. Your love has grown up for last 25 years and I believe the next jubilee of your marriage will be more exciting. Your love makes me trust in fairytales. Your mutual understanding and cooperation makes me believe in the foundation of marriage. You both give me major relationship goals and the best source to get my relationship advice from.
I never knew that you could be such an amazing husband as the amazing man you are. The way you love my sister is illimitable. Lots of love and hugs on this wonderful day my lovely old couple.
[Name of Sender]