But the Owens have done just that as the latest census figures show Park Orchards with the highest household income of any suburb in Victoria, beating affluent areas such as Toorak, Brighton and Kew.

"We moved here when our children were in primary and high school to give them space and be in a community we feel they could walk around and be safe," Roselyn Owen said.

The bucolic pocket north of Ringwood, in Melbourne's north-east, is dotted with four-bedroom homes on large blocks and mighty trees.

So, what's the secret to their high earning status? Adult children working and living at home.

In Park Orchards, more than half of households include four or more people, and 75 per cent of the suburbs' dwellings have four or more bedrooms. 

Their eldest son, Michael, is 22 and works full time as a graphic designer, while middle child Peter works part time in education support. The youngest, Sally, 19, is overseas as part of her university degree and has a casual retail job at Eastland shopping centre.

"There are definitely lots of people in the area like us where the kids are at a point where they can drive themselves, have jobs, and contribute to the house," Mrs Owen said.

Median household income measures the earnings of everyone over the age of 15 who lives in a household, meaning suburbs with a lot of dual income families will show up as higher median household incomes than suburbs teeming with one-bedroom apartments.

Park Orchards has a median weekly household income of $2660, which is $250 more than that of Toorak.

However, the median personal income in Park Orchards is $788, much lower than many wealthy areas.

Waterways, Kangaroo Ground and Sandhurst – also suburbs which have larger households – have among the highest median household incomes.

By contrast, the areas with the highest personal income were inner-city suburbs such as Port Melbourne, Toorak, Elwood, South Melbourne and Brighton, where more than half of residents earn more than $1000 a week.

The trends are especially clear when you consider that income is not necessarily the same as wealth, says demographer Glenn Capuano.

"Areas like Toorak and Malvern have a lot of older residents who might not be working any more," he said.

"We definitely saw Park Orchards come up in the last census. What we're seeing there is mature families where both parents have time to go to work as well as adult children adding to the earning of the household. That's obviously much lower in areas where one parent is staying home with young children."

Roselyn Owen said she's aware of the benefits of a multi-generational household, and the family have been discussing the option of buying an even bigger property in order to fit a unit as well as a family home.

"We are considering having a self-contained unit on a property that we could use to rent out, or to have guests stay with us, which we love, or for the family to grow, change or downsize. That might take us into the next stage of living."