Hello,
In case of SPK 40 you need to have the material extended in both the plants.
SAP recommend that you consider changing the sequence in the scope of planning so that the procurement plant is planned last. So you should always run MRP in the plant where the requirements originate first.
Please refer
Total Planning - Carrying Out the Planning Run (PP-MRP-PR) - SAP Library
Best Regards,
R.Brahmankar