Formal:
* Ma chère fille: This is the most formal way to address your daughter. It emphasizes respect and affection.
Informal and affectionate:
* Mon petit cœur: This translates to "My little heart" and is a very endearing term.
* Ma chérie: This translates to "My darling" and can be used for a daughter of any age.
* Ma fille chérie: This is a combination of "My daughter" and "My darling," and is a good balance between formal and affectionate.
Other options:
* Ma fille adorée: This translates to "My adored daughter" and conveys deep love and admiration.
* Mon trésor: This translates to "My treasure" and is a very endearing term.
The best way to write "My Darling Daughter" in French will depend on your relationship with your daughter and the context of the message.