One of the biggest gripes by many after Google brought SMS integration in the Hangouts app was the lack of merged conversations. Meaning that if you were talking to someone in Hangouts, and then the conversation switched to SMS at some point, you now had two different conversation threads to manage. A hassle, no doubt.
This week Google started rolling out an update to the Hangouts app for Android users, wherein lay the default ability of merging conversation threads. Now, I know some of us will find it hard to believe, but merged conversations aren't going to be to everyone's liking. Thankfully, Google included an option to disable merged conversations.
Using the updated version of Hangouts, launch the app and head into Settings and tap on SMS (it should be just below your Google account).
Then scroll all the way to the bottom of the page, and there you'll find the option to enable merged conversations. Uncheck the box and celebrate. Going forward, your conversations will once again be segregated.