I do believe I have licked this. No BPM and no code whatsoever. (No promises on multiple rows, though, @hmwillett.)
The business object to use is Part, and you are (pseudo) updating the PartWhse table. (NOT PlantWhse as it does not exist in the tree here.)
When I did that, I also had to add in the “Query to Object” mapping rows by hand, one by one.
I don’t have anything in the other mapping tab, except what it did automatically (part description). I’m not adding new rows here. And I had tinkered with it, but ended up making a mess, so I left it alone.
