And this might seem like an odd way to celebrate it. And you would be right; it is. I could/should celebrate it tomorrow, as an example, but that's what she will do and that's good and as it should be.
My sister, Kara, is the oldest of the second wave of children my parents had. As such we've always been linked by the notional shared responsibilities that each of us inherited through the accident of birth order. Interestingly enough we each have as a next oldest sibling, a sister and as the caboose, so to speak of our very small train of thought, a brother.
Neither of us can ever claim to have been bored while growing up in our parents' house. Lonely was also another emotion we rarely experienced. I think it was good training for the two of us.
We each married partners who were, themselves, completed human beings and not in need of finishing or fixing. Kara and her spouse have three sons (insert a musical interlude from Fred MacMurray's My Three Sons here) who have grown and are growing into adults who are interested and engaged in the world around them.
My wife and I have a son and a daughter who struggle every day to overcome the handicap of a father who still sees them as children even though they are both very much adult and in many instances far more wise about the world in which we live than their daddy-o.
We are, I have been told, the sum total of everyone we have ever met and in turn, become a part of everyone else who will ever meet us. If that's the case, I think I know where you get your cheery helpfulness and instinctive kindness from and knowing her the way I do, Kara would say 'you're welcome.' Happy birthday, sis!