Dear Abby: I have a half-sister who is 14 years younger, and there is a sensitive genealogical matter I have never shared with her. Her “father” married our mother while she was pregnant with another man’s child. That man lied to her about being single and wanting to marry her. My stepfather came on the scene, fell in love with Mom (knowing she was pregnant) and married her before she gave birth to my half-sister, which is why her birth records show him as the father.

I had urged both of them to tell her, but they kept saying it “wasn’t time,” and now they have both passed away. I’m in my 70s now and not sure about how (or if) I should approach her. I’d appreciate your advice in this delicate matter.

Sibling Situation

Dear Sibling: I advise readers to disclose this kind of information so relevant medical data can be accessed, if necessary. If you know the identity of your half-sister’s birth father and where his family is located, you should reveal this family secret so that, should the need arise, she can find out whether there is a genetic predisposition toward cancer, heart problems, etc. Her life or the lives of her children could benefit from having that information.

Dear Abby: I have two sons and a daughter. My younger son will be getting married in a few months. While he and his sister used to have a close relationship, they have been estranged since their father’s death a year ago. I have reason to suspect that he won’t invite his sister to attend the wedding.

I intend to have a heart-to-heart talk about this with my son and find out what his intentions are. I regard an invitation as not only proper etiquette, but also an opportunity to extend a peace offering.

Would you please advise me on the best way to approach him about it and, specifically, what words to use? I’m worried that if an invitation isn’t extended, their relationship may become impossible to repair. I should mention that while they are both good-hearted people, they are also stubborn.

Heartbroken Mom

Dear Mom: Whatever happened between your son and daughter must have been a doozie to have caused a yearlong estrangement. If you wish to approach your son, do so in the context of your concern that if she isn’t invited to his wedding, you fear the estrangement could become permanent. But after that, please recognize that this is his wedding, and it is his and his fiancee’s prerogative to decide who should celebrate with them.

Dear Abby: A colleague of mine died recently. I sent a sympathy card to his wife and family. The gentleman who passed away has a best friend who works with me, and they were very close — almost like brothers. They would take fishing trips together, go to football games, etc. I know the friend is grieving too. Would it be OK to send this friend a sympathy card as well? — CARING FRIEND

DEAR CARING FRIEND: I see nothing wrong with doing that. Your co-worker has obviously experienced a significant loss, and an expression of sympathy would be both thoughtful and appropriate.

Dear Abby is written by Abigail Van Buren, also known as Jeanne Phillips, and was founded by her mother, Pauline Phillips. Contact Dear Abby at www.DearAbby.com or P.O. Box 69440, Los Angeles, CA 90069.