Relating tables/portals back and forth
I have three tables - Parts, Purchase Orders, and Line Items. Whenever I make a Purchase Order, I use a portal (linking to the Line Items table) and have a drop down list of items from my Parts table that I can add to the Purchase Order (and subsequently to Line Items). The Purchase Order has a key field _kp_PO_ID that is related to Line Items' _kf_PO_ID. Parts has a key field _kp_PartID which is related to Line Items' _kf_PartID. So:
Purchase Orders::_kp_PO_ID>---<LineItems::_kf_PO_ID ; LineItems::_kf_PartID>---<Parts:_kp_PartID
I want to be able to see, from my Parts layout, which PO's that particular Part was on. So If I add a part to my Purchase Order layout (via my Line Item portal), how can I have it automatically load that Purchase Order number in a portal to the layout of that Part which was added? I'd like to do this so I can see the different Purchase Orders that the part was ordered on (say if I had 10 Purchase Orders that featured that part, I'd like to be able to see all of them listed in the portal on my Part's layout).