Here's a breakdown:
Capitalize "Family" when:
* It's a formal title: If you're addressing a specific family, such as the "Smith Family" or "The Royal Family," then you should capitalize "Family."
* It's part of a specific group name: For example, "Dear Family and Friends."
Don't capitalize "Family" when:
* It's a general term of endearment: Like "Dear Family," or "To my family."
Examples:
* Capitalized: "Dear Smith Family," "To the Royal Family."
* Not capitalized: "Dear Family," "To my family."
Ultimately, the best way to decide is to consider the context and the level of formality.