The aggregation weight property specifies the percentage of the custom member to be aggregated to the parent, with 1 representing 100%. By changing the aggregation weight attribute on the Node Attributes tab, you can modify the relationship between the selected Custom member and its parent. For example, if you set the aggregation weight to .5, only 50 percent of the value for the member is aggregated to the parent. See Defining Custom Members.
The aggregation weight for the Custom dimension can be any value (positive or negative), and fractions are allowed (for example, 1.5 is valid). The default values are 0 (no aggregation) and 1 (to aggregate). If the value is not 0 or 1, then the child member is aggregated to the parent using that multiplier.