Hi,
I know of issue linking and the possibility to use labels for filtering. Nonetheless I would be interested if it is possible in general to add a custom field where I can select a project key in a drop down or something similar.
The reason is that we have projects that contain tasks that are fixed in other projects. Instead of cloning or linking, I would prefer moving or creating these issues right in the other project and then adding such a "project link". With that in place, the original project could set up a board containg its own issues and all issues that have its project key set in the new custom field. By doing this, I could avoid loosing issues when having a typo in a label being used similar.