I also had to connect nested sortable lists.
The first approach was to do like this:
> this basically works but results in a jumpy behavior of the placeholder. Barely usable.
The second approach ist to do like this:
connectWith: '[.selectorBBB, .selctorAAA]',
connectWith: ['.selectorAAA, .selectorBBB'],
Actually this should result in a nested sortable list, where you can drag elements from the main list to the child lists, vice-versa, and between the child list. But this doesent work, as the placeholder does not appear when you drag elements from the main list to the child list and from the child list to the main list.
This second issue is described here pretty well: