Why NCS does not use Hierarchical Structure?
Hierarchical structure cannot cope with the changes in Admin structures. As a result your new data and old data cannot be linked directly due to different code and led to manual editing required.
How do I aggregate my data if there is no hierarchical information in the NCS codes?
You should have a master NCS table in which all administrative units from top to lower level with respective codes, parents admin names and parent codes in separate columns. By linking your data with this master table you can aggregate your data at any level above.
How can I link my data with my own code to new NCS code?
You create a table with all your own codes and names in columns and corresponding matching NCS codes and names in other column. You can match your names and corresponding names in NCS together with the codes by using Pcoder tools. Use this table as an intermediate table during data aggregation or importing the NCS names and codes into your table.