If I understand properly what you’re asking for, this is possible, though it’s tedious if you have to do it a lot.
In Serabale’s screen capture there’s a list of scenes, out of order: scene2, scene1, scene3. If you click the + sign under the last entry, you’ll get a popup list of all the scenes. Uncheck all the checked entries, then check them again in the right order: scene1, scene2, scene3. (Or you can uncheck scene2 & immediately re-check it, then do the same with scene3. It amounts to the same thing.)
Another thought: Not all relationships are time-based. For example, I have many events connected to people; the relationship is “Participant”. I wouldn’t want those lists sorted by the birth date of the participant — I would usually want to list them either alphabetically (by last name) or in order of importance. For me, that means hand sorting the lists the way I describe above.