The Batman Family comic was started in 1975 because of the success of the Superman Family title and ran for 20 issues form 1975 to 1978. Unlike Gotham Knights, The Batman Family comic was an anthology that told stories about different Batman related characters and didn't usually tell stories that involved a number of characters. Its role was more like The Batman Chronicles telling stories about supporting characters.

Prior to Crisis on Infinite Earths Earth 1 was the home to all of the heroes created in, or since, the Silver Age and Earth 2 was the home of all the characters created in the Golden Age. The Earth 2 characters were older than their Earth 1 counterparts; this came about because Barry Allen was inspired to become The Flash because he remembered reading The Flash comic book.

What does all of this have to do with Batman?

Pre Crisis there was an adult Dick Grayson still being Robin and Huntress was the daughter of Bruce Wayne and Selina Kyle. The Batman Family featured stories about the Earth 1 characters so Huntress didn't actually appear in the comic until #17, previously she appeared in All Star Comics which featured all the Golden Age heroes.

Batman Family contained stories featuring Alfred, Commissioner Gordon, Catwoman and ManBat. #9 featured the first appearances of the Penguin's, Riddler's and Scarecrow's daughters; they must have made quite an impression to be so completely forgotten. Even in the crazy world of superhero comics the idea of the Scarecrow having a daughter is just too weird to contemplate.

The idea of the Batman Family and of Batman as a 'father' has come in for much derision over the years, partly because the Family was such a blatant attempt to cash in on the success of the Superman Family. Batman, though, clearly is a father figure, his relationship with Robin was always more than just that of mentor and student. At the time they said that Dick was Bruce's ward, today we would say that Dick became Bruce's adopted son. Frederick Wertham in 'Seduction of the Innocent' claimed that Batman and Robin's relationship was a gay fantasy DC certainly did not intend it to be seen that way.

In response after the introduction of the Comics Code, DC effectively created a Batman Family: in 1955 they created Ace the Bat Hound; in 1956 Batwoman and in 1961 BatGirl. There was also an irritating little imp called Bat-Mite. Batwoman might, in part, have been introduced to make it clear that Batman was heterosexual, but more important were the storytelling opportunities that this offered. The editors were clearly desperate for stories that would make the Batman comics stand out so Batman was sent on stories all over the world, space and timeTrina Robbins said that they originally killed off all the woman in order to make it a little boy's club and she does have a point, but this introduction of the ultimate nuclear family, father, mother, dog and 2.4 children (with Bat-Mite as the baby) turned Batman into a fifites sitcom. Without the jokes, the intentional ones anyway.

BatGirl was probably created because if a story featured Batman, Robin and Batwoman then Robin would feel like he was intruding. The easy way to get around this if you want them all to appear in stories is to give Robin an equivalent of Batwoman, a Bat girl. Most of these spin-off characters were dropped when the new look was introduced in 1964 (the new look was the yellow oval logo and a return to fighting crime).

Over the years DC have reinvented most of their characters: the third character to have used the name Batgirl appeared during No Man's Land; Alan Grant reworked Bat-Mite and created a new dog called Ace, although I don't think he was ever actually called the Bat-Hound.