FHOG in a family partnership

I don’t know if this is possible: two family couples are wanting to take advantage of the FHOG. Both are elligable and are considering a shared mortgage, ie., between the four of them. Can both families exercise the FHOG to finance a split mortgage? Otherwise, it’s a case of using the grant for seperate mortgages. I’m assuming that it’s a “one grant per property agreement” but I’d like to know for sure. While I’m doing my homework any feedback would be appreciated.

Many thanks

Darren, Perth