Best way to say "Sending love to you (female) and your family" in German? Our families are very close, so it should be informal.
"Beste/Herzliche/Liebe Grüße an dich und deine ganze Familie"
"Beste/Herzliche/Liebe Grüße" are more personal than "Viele Grüße". I think, "Liebe Grüße" is with friends always ok.
"Tausend Küsse (an euch)"
is OK for very close friends or for areas where kisses on the cheeks are a normal way to greet someone.
"Von Herzen alles Gute für dich und deine Familie"
That is a very strong wish. I wouldn't use it often and it is more for special occasions (e.g you won't see/hear the person for a long time or they just got a baby or ...).
A comment on capitalizing "Du", "Deine" and "Dich". You can write "Du", "Deine" and "Dich" capitalized in letters, but you don't have to (Duden) (thanks to @chirlu for the correction), but as @jera pointed out "Sie" and "Ihnen" have to be capitalized in letters (Duden).
I feel "Viele Grüße" still sounds pretty flat and upstage and does not come close to "Sending love to you" but rather to "Kind regards" or similar.
I recommend in ascending strength:
Dir und Deiner Familie alles Gute
Dir und Deiner Familie alles Liebe
Ich wünsche Dir und deiner Familie liebe Grüße
Liebe Grüße an Dich und deine Familie