Sister in law are special and nice as they come from one home to another through marital bond to spread love and happiness in her new home.
Some of the samples of birthday messages for sister in law are given below:
1). Dear sister in law, wishing you a happy birthday. I hope you celebrate the special day well with my bother and I hope he has showered you with much gifts.
2). Dearest sister in law, I wish you a hearty birthday celebration with good moments. I hope you have a great celebration ahead with loved ones and a treat for me.
3). Lovely sister in law, wishing you lots of happiness on your birthday and always. Do not forget to treat me once I am thee since I missed your celebration today.
4). Dear sister in law, wishing you happiness and a hearty best birthday celebration. I pray to the Lord to give His choicest blessings of prosperity upon you.
5). Cute sister in law, I wish you a happy and a wonderful birthday. I send you gifts especially for you along with the wishes with love.