Hi Dev,
Thank you for your message. Here are my reply:
1. May has to be closed anyway.
2. If a period is closed by MMPV, there is also a way to "edit" the period from img
(path: logistics-general > material master > basic settings > maintain company codes for materials management) ... well of course this is also another "risky activity"
3. Yes, that material has only 1 GR in April. User realized it in May so the Rev-GR has to be done in May first to clear the stock and value.