The Supreme Court of NSW is the court which deals with adoptions. The website provides useful information on legal issues around adoption.
http://www.lawlink.com.au/sc
Legal Advice
The Supreme Court of NSW
Intrafamily Adoption
Community Services website (adoption ssection) provides information for step parent adoption and relative adoption; and the legal requirements for intrafamily adoption.
http://www.community.nsw.gov.au/parents_carers_and_families.html