This is my first ever post on this forum and I apologize in advance for the length of it.
I am soon to be married. We are both in our 60's and it'll be my 2nd marriage and his 3rd. He married when he was 20, but it didn't last and they divorced after a couple of years. He stayed single a long time then remarried when he was 40. They were married for 13 years. His 2nd wife died 12 years ago, leaving him with 2 young kids to raise on his own. The three of them became a very tight unit, and were very reliant on one another for support. The kids are now 19 & 21
When his first wife left him, she was a few weeks pregnant. She went on to have the baby but refused to allow my partner any access to the child, a girl. He paid what was required in child support over the years, but abided to the ex's wishes and never got involved in his daughter's life. His mother had contact with the child and would see her from time to time, but that stopped around the time she was 9 as her grandparents moved away.
That child is now in her early 40's. I found her and her mother on Facebook. They are still in the same area.
Because he never had contact with the child, there's no way of knowing if she actually is his daughter. No paternity tests were performed. He accepted she was his and paid child support for her till she turned 18.
He said he told his kids they have an older half-sister, but from what I can tell, they really have no idea. I've not discussed her with them, but from general conversations we've had, it seems clear that they believe themselves to be their father's only children.
Just as my partner has not been in contact with his daughter, she has not made contact with him. We have no way of knowing if she even knows who he is, or what her mother has told her about her father.
Or maybe the daughter is aware who he is and has chosen to stay out of his life.
I worry how his kids might react if they were to learn about their sister from anyone other than their father. She's popped up from time to time in conversation. His mother and his best friend have mentioned her to me. His kids weren't present at the time, but what if they were? They are old enough now to pick up on that.
My view is that my soon to be stepkids have a right to know they have a half-sister, but I also absolutely know it is not my place to tell them.
In addition, a few months ago my partner got himself tested for what used to be known as Aspergers, or high-functioning autism, and the diagnosis is conclusive. In a lot of cases it is genetic; it's extremely likely my partner inherited it from his father. I suggested to him that his daughter might appreciate learning of this, as it's possible that she may also show some symptoms of it. He said he'll think about it and that's where we left it.
Any thoughts on this please.