Forget about the step part because you are a true sister to me through and through! You mean a lot to me and I hope your special day is filled with the loveliest of things!
The way you welcomed me into your life will forever be the most heartwarming experience for me! You will always be a true sister to me, stepsis! Happy birthday!
I wish for the loveliest things to bless your life each day, my dear sister, but I’m wishing just that little bit more so for you today! Happy birthday!