How to update stock in storeroom.

Hello Friends,

I have a bunch of materials which our plant had bought. The PO for these materials exist in our older system(SAP 4.7) and is closed/locked.

The plant wants to add these materials to stock in the new ECC system. Some of these materials do not have existing stock in our storerooms and some of them have existing stock. How do we update our stock with these materials?

We are thinking of doing 561(initial entry of stock), please advise.

Thanks.