Ex LLPSI (Orberg) 8. Cur nemo Cupidinem pro Ascanio venientem agnovit?
Responsum meum: Facies Cupidinis mutata est ut ea similis faciei Ascanii esset. (similis + dat?)
The genitive is more usual, especially with people, but the dative is fine.
I think a more natural way to express this in Latin would be to say “facies eius in Ascanii faciem mutata/versa/conversa erat.”