"What does their stepdaughter want?"
Translation:Que veut leur belle-fille ?
...leur belle-fille? A step-daughter cannot have more than one step-parent (a step-mother or a step-father.) Kindly check this exercise, only a singular possessive, either masculine or feminine is possible in this sentence. Merci.
Maybe this questions should ask ''What does their daughter-in-law want?'' Good catch.
That is a good catch, indeed! I was mindlessly translating, and that error had not occurred to me. Nice work.
If both parents remarry, I suppose you could have two step-parents: your father's new wife and your mother's new husband.
"Demi" means "step" for siblings, demi-frère and demi-sœur.
beau-fils = stepson
belle-fille = stepdaughter or daughter-in-law
gendre = son-in-law