Yes Patrick,
You can adjust the accounting entries which made by your client a year ago by using the transaction code "F-02".
Please see the below example -
Lets say your client created a Purchase order of a single items a year ago for which inventory managed, than the accounting entries at the time of
MIGO -
Stock A/C(BSX) +
GR/IR A/C -
MIRO -
GR/IR A/C +
Vendor A/C -
Consumption -
Stock A/C -
Coonsumption A/C +
Now While doing "F-02"
You just need to do the entries -
Consumption A/C -
Stock A/C +
after making these entries your entries for the particular materials are being nullified.
Please take the little help from your FI Consultant also to post the entries in Previous period.
Thanks & regards,
Ankur Chauhan