Adding the capability to 3PL for customers to our SD/LE/IM/WM setup

Question

Looking to solve a problem where we perform the service of a 3PL for our customers.  Our customer stocks inventory at our warehouse (IM/WM implementation) and will subsequently place orders for us to deliver (with WM TO) materials to their locations for their production process.  They own the stock, we just store and provide logistic serves for them. 
Additional considerations:
u2022A specific material number may be something we make, stock and deliver(own stock), we may also sell and transfer that stock to a customeru2019s(3PL customer) inventory for them to subsequently order to be delivered. 
u2022Customers 3PL inventory will be non-valuated
u2022Solution should be scalable to new 3PL customers via master data setup, not having to configure.  Meaning we want to avoid creating a separate non-valuated plant for customer 3PL stock and managing the individual customers a within different storage locations or some other logical way of breaking the stock out by customer.
u2022Inventory visibility by material can be distinguished between own stock and specific 3PL customer stock.
We are using industry solution u201CFabricated Metalsu201D also referred to often as Mill Works.  Within that solution there is a Special Stock Indicator u201CBu201D(Customer Stock) defined in the system.  There is documentation of itu2019s use within subcontracting business processes but it also appears to be a workable solution for our needs.  We are able to MIGO inventory into the system for 3PL customer stock using SOBKZ=B, however the 601B movement for a delivery is not supported. 
Itu2019s arguable that some sort of custom movement type(for example 901B) could be created and tied to a delivery schedule line category as a potential solution with the requisite item category setup to support it.  I may be missing a few more details to that setup.  Our thoughts are this is not a unique requirement and someone must be doing similar 3PL services on an R/3 system and SAP does have a clear vision of how this process should be designed in the system.
Any input or experiences you can share are appreciated.

Answer 1

Dear Myles,
This can be done in two way and both we have suggested for one of our leading client.
1. First Process:
a). Kindly create PO with confirmation key "0004-Inbound Delivery". -ME21N
b). Inbound Delivery treated as a ASN and here we have appended fields to capture transporter details. -VL31N
c). Goods received from vendor then the transporter has to acknowledge the ASN through customized transaction and system will given acknowledgment number. (Custom Transaction for Acknowledgment)
d). Once acknowledged the ASN details like Qty, Price, Invoice number, Weight, No of cases, Mode of Transport, Transporter Name and LR numbers will be captured in customized table and display incustomized report.
e). After reaching 3PL warehouse then the transporter has to confirm ASN and ensure above details are correct. (Custom Transaction for Confirmation)
d). Customized report treated as 3PL stock overview report and it contains all above information with Acknowledgment and Confirmation.( Here we can come to know if any transit or confirmation pending details). (Custom Transaction for 3PL stock Visibility)
e). Based on the requirement received from customer the stock will be supply from 3PL warehouse. (MIGO at customer end)
2.  Second Process through Rough GR:
a). Kindly create PO with confirmation key "Rough GR/Inbound Delivery". - ME21N
b). Inbound Delivery treated as a ASN. - VL31N
c) Create Rough GR with IBD at 3PL warehouse  - VL41
d) Once Rough GR made then the corresponding IBD stock is consider as 3PL stock and stock visibility can be done through customized transaction.
e) Based on the requirement received from customer the stock will be supply from 3PL warehouse. (MIGO at customer end)
Hope it is clear.....
Regards,
Karna J