You’re so much more than just a sister-in-law to me! I hope you have the happiest birthday, my true sister!
Happy birthday to the prettiest, most stunning sister-in-law ever! Your beauty is enchanting, my dear!
To my kind, sweet, and thoughtful sister-in-law on your special day, I’m sending only the greatest birthday...
Happiest of birthdays to you, sis! It’s so wonderful to be able to call you sister, but really the truth is...
Day
Month ---- January February March April May June July August September October November December