Unfortunately, this is currently not possible in Google Classroom. You must remove the student from the current class and let them join the new one. All work is kept in the Classroom folder on Drive.
Can you transfer students to Google Classroom?
You can easily move students from class to class. If you have the same assignments in all classes, all student work will be transferred. Important: Google Classroom and Clever require students to be moved to these apps before syncing the roster to Actively Learn.
Can you combine classes in Google Classroom?
Unfortunately, merging classrooms is currently not possible in Google Classroom. If you have feedback or want to request a class merging feature, you can use the ? in the lower-left corner of your Google Classroom and select Report a problem or Request a feature and explain here.
