Nice work!
Unfortunately automated unchecking of parent checkboxes is not possible at the moment. I usually recommend a custom code snippet where I can, but this might be a bit more complex as not only the checkbox but the state has to be updated so it’s not sent as “checked” to the back-end.
It shouldn’t be too hard to implement though in the code, I will take this as a feature request, I will try to add an option to the back-end to enable this behavior in the upcoming version.