[Pontiac]

They have a great deal more of new info to absorb, than we do, as well as to decide about asking the mother. Also about telling their own siblings, children, etc.

I would always advise keeping this kind of news to yourself until the unfaithful and his/her spouse has past on.

It is most likely that relationships will suffer. I would advise this half sibling of yours not to reveal this to his/her half siblings. It isn’t worth the chance that their relationship with their parent would suffer.

Grandchildren certainly do not need to know this kind of thing.

Honor your father and your mother. I think keeping their secrets falls in to that huge and very important commandment.

[Pontiac]

They have a great deal more of new info to absorb, than we do, as well as to decide about asking the mother. Also about telling their own siblings, children, etc.

One thing to recommend to the half-sibling if she has already revealed that he knows of the extra marital status of his conception to his mother is to ask the mother to wright a letter to the other children to be read after her death telling the story.

After her death, the others can and perhaps should know the truth. But if the mother prefers that the other children not know, I think that I at least would honor her wishes.