Screen Customisations in Kinetic

We have had a screen customisation done with a BPM behind it on ‘Part’ for instance and rather than adding the customisation through the menu option like we have done before in E9 we had had to have new menu options created? I would like to understand why this has to happen this way as potentially if you are having to create new menu options to replace existing ones, it could be a lot of extra maintenance when you further customise the screens whereas in E9 you just update the existing customisation.