सुधीर चंद्र कर

Sudhir Chandra Kar (1906–1977) was Rabindranath's amanuensis at Santiniketan through the final years. By then the poet's hand was failing; he composed aloud, and Sudhirchandra wrote — poems, letters, and songs as they were made.

That places him at the exact point where several of these songs enter the written record. His name on a notation means he was in the room.