Communication is critical. Your team can't hit the goal if it doesn't know what it is. Have a family meeting and take the time to discuss income limits and higher objectives, such as family vacations and college. Then work to get everyone on-board with some brainstorming. Ask everyone to contribute ideas for cutting expenses or changing the usual routine to make it more cost efficient. A feeling of ownership in the plan will boost your players' efforts in making it work. Then, assign individual and team responsibilities based on each person's abilities and interest.