How to send and reply to SMS shortcodes using Google Hangouts on Android 5.0.1?

I am on a Nexus 4 running Android 5.0.1 and using Hangouts. I cannot figure out how to send an SMS to a shortcode and how to reply to it. I have tried adding a "+" to the shortcode, and it lets me send it. However, the response comes in a different thread and does not let me reply. Has anyone gotten short codes to work with Android 5.0.1 and Hangouts? If so, then how?