Step 1: Long press on one of the conversations that you want to merge with another thread. Once it has been highlighted, select the second thread as well. Keep in mind that the threads must be a combination of a Hangout thread and SMSes. It is not possible to merge two Hangouts threads into one at this point. You can, however, merge two threads from different senders into one.
Step 2: Tap the Merge option that you see on the top right in the action bar to combine the conversations. And that’s it! The new update for Hangouts brings with it quite a few other features including a home screen widget and performance improvements. Make sure to read about them here.
