Ways to Aggregate and Disaggregate in Level-By-Level Planning 
For a brief outline of aggregation and disaggregation, see
Concepts of Aggregation and Disaggregation.In leve-by-level planning, manual intervention by the user is required for both aggregation and disaggregation.
You can use the planning table function Edit
® Disaggregate line to disaggregate data and a self-defined macro (created in the planning type) to aggregate data. Disaggregation is carried out on the basis of the proportional factors stored in the planning hierarchy master record.See also:
Implementation Guide for Sales & Operations Planning
("Set parameters for info structures and key figures")Automatic Calculation of the Proportional Factors in Level-By-Level Planning
Calculating the Proportional Factors Automatically