I keep hitting gaps in your description and having to guess at what you mean. For example, you say there is a relationship between 2 tables and then list what could be up to 4 tables in two different relationships:
Storeroom < Inventory table
Trans_OE < Line item table from the sales order
and none of these are named "Storeroom Trans_OE_Part#CC"
I suggest uploading a screen shot of Manage | database | Relationships--cropped to just the relevant table occurrences and then please identify which table occurrences go with each layout and each portal from what you have already uploaded.