i think a good start would be to mention how the concept of the family has changed over time and as more family arrangements emerge, the law has to change in order to somehow accomodate for it and hence, there is no real one definition for family
then i would say, go on to start talking about alternative family arrangements - nuclear families, blended families, single parent families, de facto relationships, same sex relationships and any others if ive missed out of em
and in terms of being recognised by the australian legal system, just say how most are, but some are given more recognition for example marriages over same sex relationships. referring to certain acts here would be good. you could also mention how some werent recognised before but now they are, for example people in same sex relatinoships are given the same rights as heterosexual de facto couples under the Property (Relationships) Legislation Amendment Act 1999 (NSW) or how single parent families are more accepted today whereas previously it was seen as a result of immoral activity
in terms of analysing the effectiveness of legal remedies, you need to first know the remedies (which i don't) and the remedies will directly relate to the issues of each family. for example, issues facing single parent families would be access to welfare payments, and you can possibly analyse the effectiveness of centrelink ? i'm not too sure about that cause i don't really know the remedies
but yeah, thats how i'd approach the Q
hopefully that helps