Hi Ramesh,
Rahul and Anand has put forward some important questions before you decide anything.
If at all it's required I can propose some crude custom logic for you to explore further -
a) Create 18 different inspection plans with different quality specifications to capture results. Link your material & vendor with it. You can create GrC's as well, but you should maintain at least 18 different combinations.
b) Create 18 different inspection types of origin "01" (Ex: 0101, 0102, ..or V01, V02...) and assign them to the inspection lot origin "01".
c) Create a Z table where you maintain the Sub-Vendor names/codes Vs Inspection types created above.
d) While doing GR for the same PO, there should be an unique identifier or item Text field always populated, to uniquely identify which sub-party has send this material for the main vendor.
e) Now your GR User Exit understands based on the above input field in MIGO & Z-table combination, which inspection type should be selected, and you can get a inspection lot, per sub-vendor.
Further inputs for your analysis:
i) You can reconcile for any particular inspection types, how are the results going on.
ii) Uniquely manage each inspection plan and later you have the flexibility to maintain these inspection plans.
iii) You can develop unique quality reports based on sub-vendors.
iv) Client can send these quality analysis to the main vendor on periodic basis, for it to take necessary actions on it's sub-vendors.
Thanks,
Arijit