• Login to your support portal. 
• Open the Tickets tab. 
  
• Select the tickets you want to merge from the list by using the checkboxes.
  
• Click on the Merge button on the navigation pane.
  
• In the dialog box that pops up, choose which ticket you want to be the primary ticket by clicking on it. A tick mark appears next to it confirming that it has been done.
  
• If you'd like to remove any tickets from the merge, you can do so by clicking on the red minus icon next to them from the list. You cannot remove a ticket from the merge when it has been marked as primary. 
  
• Similarly, you can use the search box on the right side to lookup tickets by either Requester name, ID or Description, and add them to the list. 
  
• When you are ready to proceed, click on the Continue button. 
  
• When tickets are merged together, a note is added to the primary and secondary tickets. You can edit the content in each of them if necessary.
• Finally, click on the Merge button to finish merging the tickets together. 

Another way to do this is on the main tickets page you can click in the box next to the tickets you want to merge and on the top of the page click merge