"Is she your younger daughter?"

Translation: Вона ваша молодша донька?

[georgefromba]

"Це ваша молодша донька? " should be right as well.

[mapple2002]

Unfortunately not, because the English sentence given includes 'she', which is not present in the sentence "Це ваша молодша донька?"

[ttyieu]

Is "це твоя молодша донька?" wrong?

[chrislem1972]

Вона твоя молодша донька?

[Ukurainajin]

Yes, ‘ти’ and ‘ви’ are both ‘you’. Hence ‘your’ in this sentence can be either ‘твоя’ or ‘ваша’.

[chrislem1972]

Вона твоя молодша сестра? Correct?

[Michal828238]

Incorrect. "... молодша донька."