It's important to note that this term is not commonly used in English-speaking contexts. The more standard terms used for secondary authors are:
* Co-author: Used when two or more authors contribute equally to a work.
* Contributing author: Used for authors who contribute to a work but not as the primary author.
* Collaborator: A broader term used for anyone who works with another person on a project.
Therefore, the best English equivalent for "Duyyam Nibandhak" depends on the specific context and the role of the secondary author.