Hello @LisaWild 

Are you talking about grading a discussion in speedgrader? By default, the student posts should populate in speedgrader per student. If it doesn't show and says "view full discussion" it may be a way you set it up. Is it a group discussion? Are all students in the appropriate group? If a student was left out but still replied, their posts won't populate in speedgrader. If you're not talking about speedgrader at all, you just mean threaded reply posts? It may depend on the discussions that are set up at the admin level. If threaded replies do not automatically populate in full, unfortunately you may just need to click "view replies" to populate them. Some discussions have hundreds and hundreds of replies and this is to save space and loading times. You may want to speak with your institution or Canvas Support directly who can look at the specifics of these discussions and the setup on an admin level. 

https://community.canvaslms.com/t5/Canvas-Basics-Guide/How-do-I-contact-Canvas-Support/ta-p/389767