"De eerste vrouw van mijn vader is de moeder van mijn halfzus."
Translation:My father's first wife is my half-sister's mother.
I don't know if reporting the problem explains why i flagged it. But I wrote this "my fathers first wife is the mother of my half sister" and the notifications says there is a mistake because I put a space between "father" and "s". Which I clearly did not. If it wants to call me out for anything, at the very least call me out for the missing apostrophe!
The new Dutch tree is very buggy still. They're trying to fix small errors like that.
Sorry, it may be because of my neck of the woods, but ...half-sister is not a a term generally used to describe a stepsister. Stepmother/stiefmoeder would make me believe that stepsister/stiefzus would be a more apt description in such situations.
A half sibling is one that shares one biological parent but not the other. A step-sibling does not share any of the same biological parents.
This sentence implies that she/he and her/his sister come from the same father, but not mother.