Need to capture Supplier inspection plan using supplier portal , using deliverables so that buyer ca

Summary

Need to capture supplier information using supplier portal

Content

PO has been provided to Supplier .Supplier has acknowledged the purchase order. Supplier manufactures the product ,complete inspection of product. Supplier need to share inspection plan to buying organization say buyer .Buyer need to check inspection plan & confirm & then supplier will initiate ASN.

I tried using deliverables fuctionality on PO ,Created  external type of deliverable while creating PO.I have observed supplier user can view it under Manage deliverable section on Supplier portal  & also can attach file as response say inspection result & change status from Open to Submitted.

Buyer of PO got notification but same is not editable ( Just FYI notification)and buyer can't see attachment attached by supplier user in deliverable. How same can be achieved?