- Edited
Hello @ntozier, thank you for the tip, that worked.
I did look around the ticket page before posting, but it turns out I had the required permission turned off (along with the linking tickets permission) for some reason, so that's why I haven't discoved the button myself.
Here's the relevant documentation in case anyone's coming from search: docs.osticket.com/en/latest/Features/Ticket%20Merge%20&%20Link.html