Thanks Alan for your advise, but I'm not sure how I would implement what you are suggesting?
For now I use smartgrid's onpdate and oncreate events to update purchase order "items" field (type list:string) with all items for that particular order, but I hate this solution since it's computed value. This way I can product csv easier, but would rather flatten two tables into one at the time when the report is run. Thanks once again... and i'm still open for more suggestions, if anyone has any idea. Adi