When one of the applicant is permanent resident of Australia and none of the applicant claimed for FHOG before are eligible for first home owner grant. There are 2 types of grant offered by Australian government. One id from Commonwealth government and other is by the state government of each state. Applicant need to check their statement revenue website to find current offers for first home owners grant and eligibility criterion.
Following are links to state revenue offices to read more about first home owners grants