If you are the main applicant, the visa application can include your family. The dependant family unit can include:
Spouse (legally married or in de facto relationship)
Dependant child (natural, adopted or step child) who is under 18 years of age
Other dependants if they are wholly or substantially reliant on you for financial support for their basic needs of food, clothing and shelter and they have been reliant on you for that support for a substantial support.