@solth I played a little bit with this feature. One question which came to my mind: Do we need another layer of permissions here? It seems to me that everybody who is allowed to change structural data can easily delete processes from a superordinate unit. I would prefer if there is a special permission for that.
And how can a link be reestablished after deletion? Is this possible at all?

Edit: I am wondering wether the interface for adding "structural elements" to superordinate units should be different than the one for "normal" processes. What is needed is a way to add subprocesses, not new structural elements, to actually establish a link between processes. But maybe i am overlooking some feature.

Edit2: I just noticed that it is (also in current Master) possible to add images and strucural elements to a superordinate unit (e.g. a multi volume work). This leads me to the question: Is it actually desired that elements can be freely added to superordinate units, when the ruleset allows for that? Or are superordinate units more restricted in the sense that they only hold metadata and pointers to subordinate processes and should not contain e.g. images?

@BartChris thanks for the comments.

Yes, it is already possible to (re-)establish links to subordinate processes directly from the metadata editor, and in fact it is possible from the very dialog that can be seen in your screenshot. You just have to check the checkbox "Verlinkung" and the GUI of the dialog will change to one that allows you to add process links. This means it is quite easy to create links between parent and child processes, even if a link was accidentally removed.

Because of this I am not convinved that we need another, separate permission to control whether links between processes can be removed (and added, for that matter), but this is probably something that the users are better suited to decide than me.

Concerning the question of your second edit: that is how Kitodo 3 is designed: only the ruleset controls what structures can be contained in another structure or document. This is of course something which can be discussed, but it something which is currently at the core of Kitodo.Production.

@solth Thanks a lot for your explanation, i forgot about that. While checking that i encountered a bug in the search functionality, for which i made another issue. #5509

You are right that the restoration of links to sub processes is quite easy (if the search function is repaired), but i still am afraid that the deletion of a process link might happen by accident and stays unnoticed. But maybe others have a different opinion on that. We already had a similar discussion here (#5406). The main problem here is for me, that i cannot really control who is able to call the destructive operation of deleting a link between processes (basically everybody who is allowed to edit the structure tree) while in case of the deletion of images i can give this right only to specific persons.

The general feature of adding images to a super-ordinate process, is probably better discussed in a GitHub discussion.

@andre-hohmann thank you for the review!

The error message described in #5509 could not be reproduced.

@BartChris already fixed that issue with PR #5514 which has been merged into the master branch. This branch has been rebased against the updated master.