Go to the Main Menu and enter s to Setup and then enter c for Config . Put your cursor on the first message you want to include in the group. S status Say you want to select 10 posts and they have no text in common, not any other feature in common.
Press z to zoom in on the selected messages.
Press z to zoom back to your original mailbox. I often use the T for Text selection in Step 2 above. In this example I want to select based on the text appearing in the subject line. In response to that prompt I press the s key to indicate I want to base my selection on the subject line.