How to add members in classic workspace dynamically

Hi,

I want to add 50 memebers to my classic workspace.

Challenges:-
1.I don't want to add all 50 members manually.
2.I also don't want to create a DL of 50 members as we may require to change the permission level from member to admin or admin  to whenever needed.
3. Adding manually all the 50+ members is painful.

Please suggest.

Regards,
Amit