P filed Chapter 13 bankruptcy in September 2010. P's ex-husband, Zimmer (D'), objected. D claimed the proposed plan overstated P's household size, resulting in an inaccurate calculation of her monthly expenses. P and D share joint custody of their two minor sons. Neither party pays child support; they share 'expenses for clothing, school supplies, and other incidental expenses for their sons based on where the sons live when an expense is necessary.' Out-of-pocket medical expenses are divided equally. P's sons reside with her and are in her care and custody for 204 days each year. P's current husband has joint custody of three children from his previous marriage: two minor sons and a nineteen-year-old daughter. P's step-children reside with her and her husband approximately 180 days per year. P claimed a household of seven members. D claims P's plan should use a method that better approximated the actual economic impact of each individual on P's expenses. Such an approach would result in a lower calculation of her monthly expenses such that she would have income available with which to pay toward her unsecured debts as part of a proper Chapter 13 plan. The bankruptcy court observed that the Code does not define 'household.' The bankruptcy court adopted a variation of the 'economic unit' approach, first assessing the number of individuals whose income and expenses are intermingled with P's, and then calculating how much time any part-time residents were members of P's household. In adopting the 'economic unit' approach, the bankruptcy court noted that other definitions were inconsistent with the purpose of the Code and were the least flexible in terms of adapting to an individual debtor's circumstances. The court held that the economic unit approach best 'captured the nuances of familial support and bonds' and enabled the court to 'account for dependents who reside with the debtor on a part-time basis . . . in calculating variable costs such as food, utilities, and out-of-pocket health care expenses.' The court determined that each of P's two sons constituted .56 members of P's household (residing with her 204 days out of a possible 365) and that each of P's three step-children constituted .49 members of her household (residing with her 180 days out of a possible 365). Thus P had a total of 2.59 children in her household full-time, which the court then rounded up to three children. It held that the household was 5 members. The bankruptcy court certified the issue of the determination of the 'household' size for direct interlocutory appeal.