First of all: add next section to composer.json:
  "repositories": [
    {
      "type": "vcs",
      "url": "https://github.com/SCIF/admin"
    }
  ],
Add package by composer: composer require globalsdd/admin dev-development.
Next installation steps similar like in docs: http://sleeping-owl.github.io/v3/
You can use belongsTo and hasOne relations in FormItem:
    ->createAndEdit(function($id) {
        $form = AdminForm::form();
        $form->items([
            FormItem::text('name', 'Name'),
            FormItem::text('page.slug', 'Slug'),
            FormItem::text('page.title', 'Title'),
Page is belongsTo relation of main described model.
If you will find bug or just interested to develop it — create issue ticket at https://github.com/SCIF/admin/issues