You may choose an artifact that acts as a "parent" to the current artifact. You first select the project to which the parent artifact belongs. When you hit the "Search" button you will get a list of artifacts including their synopsis from which you can choose the one you want to act as the parent.
You may use the filter functions provided to limit the selection list to more quickly find the parent artifact.
Changes are only reflected in the "Choose Parent" window. The main edit page is updated only after a reload action.