Hi Joy,
I checked the provided sample data in both iri_stock_models , stock_models and stock_model_details, the only different data is the ‘METHOD’. It is ‘D’ in stock_models, ‘C’ in iri_stock_models.
It seems that you were trying to update this field in the old stock models by uploading a same stock model with a different METHOD value.
If this is your concern, you can set the system parameter 'ALLOW_MASTER_CHANGES_UPLOAD' from ‘N’ or ‘Y’, this will allow you to update existing stock_models records.
Please notice that if two stock models have same bu/style/color/dimension/size/site, these two stock models will be treated as the same stock models even though other values maybe be different.