How to get group parent

[ArtMin96]

How to get the group parent after dragging into another group?

[
    [
        'order' => 1,            // order of group (starts at 1, not 0)
        'value' => 20,           // group id
        'items' => [
            [
                'order' => 1,    // order of item within group (starts at 1, not 0)
                'value' => 50,   // item id
            ]
        ]
    ]
]

Also, groups that do not have a parent cannot become children of another group. How can I fix that? I use this part Multiple draggable groups with draggable items