Show MR in issue board

What is the simplest way to add a Merge Request as an item in an issue board?

Sometimes an MR is put up from a developer outside my team and they want someone in our team to review it. In this case I want to add the MR to our team issue board to visualize the work that needs to be done. How can I do that?

Why aren't MR:s handled the same was as Issued here? I added a label to the MR, but did not make the MR show up in the board.