Need Help: Father's Lost Marksheet and Admit Card Required for Mother's Pension

Hello everyone, I'm in urgent need of advice regarding my late father's Madhyamik Pariksha marksheet and admit card from 1988. He lost these documents in 1991 but got his government job as a primary school teacher in 1999 with the pass certificate. Sadly, he passed away on September 2, 2024. Now, these documents are required for my mother's pension. I approached the regional office of the West Bengal Board of Secondary Education with all necessary documents to request duplicates. However, they said they do not provide duplicate marksheets or admit cards for deceased individuals, even after explaining the importance for the pension process. Has anyone faced a similar issue or knows any way to resolve this? Your advice or suggestions would mean a lot. Thank you!