Procurement on behalf of other Company

Dear team,
Below is my query which is challenging to map in SAP.
Pls sugges solution.
1. My client A is procuring materials on behalf of his parent company B. Vendors raises bill on Company B.
2. But all the procurement activities are doing by Compnay A. These materials will be used by Compnay A for carrying out work.
3. So Comapany A wants all the transactions [PO tracking/GRN with values/invoicing] to be captured in his Company code but without effects in trial-balance sheet.
Pls suggest


If the Compnay A is raising the PO then the vendor should also send the bill to Compnay A.
If compnay A is purchasing on behalf of company B then you can maintaintain Compnay B in the PO and maintain the Plant of Copmnay A in the iteme level.
So if you do the GR this will go into company A,  and when you post an invoice this will be posted in Company B.
For this kind of postings intercompnay configuration to be completed by FI.
I am not sure if this process being followed is leaglly acceptable. Please check with Finance if this is the way they would want the process
Thanks & Regards