Hello,
If you are using ESOA (XML) to create POs in ECC from shopping cart, cart status is updated with XML confirmation message, which comes from ECC after PO is created.
Message PurchaseOrderERPConfirmation_In would update cart item status.
You can read more informormation about this in KBA 1676004.
After PO is deleted in ECC, shopping cart item status should be updated with "follow-on document deleted". Is this occurring?
Report BBP_SC_AUTO_RETRANSFER would help to process shopping carts in status I1111 (which is a temporary status). This report will try to retransfer the cart and after certain number of failed attempts, cart status would go to I1112 (error in transmission), then administrator would be notified and cart should be retransferred via Shopping Cart Monitor or Application Monitor.
Regards
Ricardo