If you are transferring i.e. not arriving or departing from Hamad Intl. Airport; you are allowed to carry alcohol with you. The limit is 5 ltr. per person.
You will not be allowed to leave the airport with the alcohol.
As a transfer passenger you may carry alcoholic beverages in your
baggage. However these must be packed in containers of less than 5
Please note if you intend to exit the airport and visit Qatar before
continuing your journey, then alcoholic beverages cannot be brought
into the country under any circumstances. These will be confiscated
and you won’t be able to retrieve them at any time.
If you’re travelling to Australia and have purchased alcoholic
beverages or cosmetics from an airport other than Hamad International
Airport, then these will be confiscated at your onward flight’s
boarding gate. This procedure is in accordance with Australian
source : http://dohahamadairport.com/airport-guide/at-the-airport/security-customs
So you're allowed a total of 10 liters of the beverage (5 you, 5 your wife) during transit.