Yes. If you are an Admin in Literably, you can pull students from other classes into your class list.
When you login to your Literably account, at the bottom of the page you should see a list of the teachers at your school. If you do not see this list, you are not an Admin. Please email firstname.lastname@example.org to request Admin privileges.
To add a student to your class list, click on the teacher's name to load his/her class list. Then, click the checkbox next to the student's name and click the blue Add to Your Students button along the top. The student record will be "copied" so that it appears in your class list. (See red arrows in screenshot below.)