Hi @ChrisNguyen1 

Speedgrader doesn't have such a filter, but in the Gradebook itself you can filter on Sections or Student Groups (under the View menu, or Enhanced Filters if it is enabled), and there is nothing preventing you from adding students to student groups at any point during the course.

See https://community.canvaslms.com/t5/Instructor-Guide/How-do-I-use-Enhanced-Gradebook-Filters/ta-p/513... 

https://community.canvaslms.com/t5/Instructor-Guide/How-do-I-filter-columns-and-rows-in-the-Gradeboo... 

https://community.canvaslms.com/t5/Instructor-Guide/How-do-I-manually-create-groups-in-a-group-set/t...