In your example - the plant Tank Heel has been filtered in the primary data source. As a result, the value is not available for the view without addressing the data. In the attached workbook, I have duplicated the data source and utilize a calculated field on the secondary data source for returning just Tank Heel. I have made one view that utilizes a reference line so the value appears across the entire viz and then in another, I have utilized the value itself so that it appears for the related dates/rows that it exists in the data. You could get more detailed by using a parameter to select the plant from the secondary data source and then the line could move around depending on plant selection for the end user as well. This has been done on the reference line sheet example for you with a dynamic title to indicate the comparison:
I hope this helps.
LAR Inventory Packaged_v10.5_PV.twbx 353.6 KB