1:1 relationship with woocommerce product types

Hello!

There are some built-in product types in WooCommerce: simple, variable, external. I'd like to create a vica-versa relationship with one product to another, based on product type. The simple products should be paper-based books, while the external products should be books sold digitally (ebook).

If I use this code, two META BOX apperas, and I can select the elements, but this is not OK, because I do not want to see tho boxes. When I set the 'reciprocal' setting to true, only one box appears, but the same on both product types. How can I solve it so that only the right one is displayed?

\MB_Relationships_API::register([
  'id' => 'simple_product_to_external_product',
  'reciprocal' => false,
  'from' => [
    'object_type' => 'post',
    'post_type' => 'product',
    'meta_box' => [
      'title' => __('Paper based version', 'my-plugin-textdomain'),
      'context' => 'normal',
      'priority' => 'high'
    ],
    'field' => [
      'name' => __('Product', 'woocommerce'),
      'placeholder' => __('Select a paper based version', 'my-plugin-textdomain'),
      'query_args' => [
        'tax_query' => [['taxonomy' => 'product_type', 'field' => 'slug', 'terms' => 'external']]
      ],
      'max_clone' => 1,
      'js_options' => [
        'placeholder' => __('Select a product', 'my-plugin-textdomain')
      ]
    ]
  ],
  'to' => [
    'object_type' => 'post',
    'post_type' => 'product',
    'meta_box' => [
      'title' => __('Digital (eBook) version', 'my-plugin-textdomain'),
      'context' => 'normal',
      'priority' => 'high'
    ],
    'field' => [
      'name' => __('Product', 'woocommerce'),
      'placeholder' => __('Select a digital (eBook) version', 'my-plugin-textdomain'),
      'query_args' => [
        'tax_query' => [['taxonomy' => 'product_type', 'field' => 'slug', 'terms' => 'simple']]
      ],
      'max_clone' => 1,
      'js_options' => [
        'placeholder' => __('Select a product', 'my-plugin-textdomain')
      ]
    ]
  ]
]);