Creating reports that the ERP is not able to create is not difficult.   These are the concepts and processes I use in the Sakamoto ERP Solutions to accomplish this.  The pieces are:

1) Use a Data Warehouse (DW) that stores ERP data and other data, including data that does not exist in the ERP.
     * New fields are often difficult to add to the ERP itself. In that case just add it to the DW.

2) Design and create process to get the new data not available in the ERP into the DW.
     * I often accomplish this with custom data input screens. Including a form similar to a Journal Entry. It has the usual fields, plus new fields for data missing from the ERP.

3) The new custom data input screens feeds the data into both the ERP and separate DW as needed.
     * Now the DW has add'l data that the ERP does not have.

4) Have someone with knowledge of Database, Programming, Accounting and Auditing to design and create the reports using the data in the DW.
     * Now you can create every missing report that you need.