Create multiple listings in report to one and adding the corresponding values

[evandergoot]

I have a database that contains the complete buildup of a machine. in this machine specific parts are used multiple times at different levels.

now when a Bill Off Materials (BOM ) is generated, the parts and their values are shown at their own positions.  For building this is great, for purchase not so. 

What I need is the report to show a single line of each part but the amounts of each instance summed up to one value.

any Ideas ??