Linking and embedding two custom post types with the REST API

Question

Hope you are having a great day!

I am developing a theme and in my functions.php, I have registered two custom post types—modules and sessions—like this:

    register_post_type( 'module', [
        'labels' => [
            'name' => 'Modules',
            'singular_name' => 'Module',
            'add_new' => 'Add New Module',
            'add_new_item' => 'Add New Module',
            'edit_item' => 'Edit Module',
            'new_item' => 'New Module',
            'view_item' => 'View Module',
            'view_items' => 'View Modules',
            'search_items' => 'Search Modules',
            'not_found' => 'No modules found',
            'not_found_in_trash' => 'No modules found in trash',
            'all_items' => 'All Modules',
            'archives' => 'Module Archives',
            'attributes' => 'Module Attributes',
            'insert_into_item' => 'Insert into module',
            'uploaded_to_this_item' => 'Uploaded to this module',
            'filter_items_list' => 'Filter modules list',
            'items_list_navigation' => 'Modules list navigation',
            'items_list' => 'Modules list',
            'item_published' => 'Module published',
            'item_published_privately' => 'Module published privately',
            'item_reverted_to_draft' => 'Module reverted to draft',
            'item_trashed' => 'Module trashed',
            'item_scheduled' => 'Module scheduled',
            'item_updated' => 'Module updated',
            'item_link' => 'Module Link',
            'item_link_description' => 'A link to a module',
          ],
        'menu_icon' => 'data:image/svg+xml;base64,' . base64_encode( file_get_contents( get_template_directory() . '/assets/icons/module.svg' ) ),
        'menu_position' => 20,
        'public' => true,
        'supports' => [ 'title', 'thumbnail', 'excerpt' ],
        'show_in_rest' => true,
        'rest_base' => 'modules',
      ] );
    register_post_type( 'session', [
        'labels' => [
            'name' => 'Sessions',
            'singular_name' => 'Session',
            'add_new' => 'Add New Session',
            'add_new_item' => 'Add a New Session',
            'edit_item' => 'Edit Session',
            'new_item' => 'New Session',
            'view_item' => 'View Session',
            'view_items' => 'View Sessions',
            'search_items' => 'Search Sessions',
            'not_found' => 'No sessions found',
            'not_found_in_trash' => 'No sessions found in trash',
            'all_items' => 'All Sessions',
            'archives' => 'Session Archives',
            'attributes' => 'Session Attributes',
            'insert_into_item' => 'Insert into session',
            'uploaded_to_this_item' => 'Uploaded to this session',
            'filter_items_list' => 'Filter sessions list',
            'items_list_navigation' => 'Sessions list navigation',
            'items_list' => 'Sessions list',
            'item_published' => 'Session published',
            'item_published_privately' => 'Session published privately',
            'item_reverted_to_draft' => 'Session reverted to draft',
            'item_trashed' => 'Session trashed',
            'item_scheduled' => 'Session scheduled',
            'item_updated' => 'Session updated',
            'item_link' => 'Session Link',
            'item_link_description' => 'A link to a session',
          ],
        'menu_icon' => 'dashicons-microphone',
        'menu_position' => 20,
        'public' => true,
        'supports' => [ 'title', 'editor', 'custom-fields' ],
        'show_in_rest' => true,
        'rest_base' => 'sessions',
      ] );

Modules and sessions can then be requested with the REST API by using requests like:

• https://<site-domain>/wp-json/wp/v2/modules?_embed=wp:featuredmedia,wp:term&_fields=id,slug,date_gmt,title.rendered,_links,_embedded
• https://<site-domain>/wp-json/wp/v2/sessions?_embed=wp:featuredmedia,wp:term&_fields=id,slug,date_gmt,title.rendered,_links,_embedded

My problem lies in the fields _links and _embedded of the returned JSON which, for instance, look like this for a post that supports featured images:

"_links":{
    ...
    "wp:featuredmedia":[
       {
          "embeddable":true,
          "href":"XXX"
       }
    ],
    ...
},
"_embedded":{
   "wp:featuredmedia":[
      {
        ...
      }
    ],
    ...

A module is a collection of 0..* sessions and a session can only be part of one module. I need to make this one-to-many relation available with the REST API through the _links and _embedded fields. The request should return a JSON looking like this for a particular module:

"_links":{
    ...
    "custom:sessions":[
       {
          "embeddable":true,
          "href":"XXX"
       }
    ],
    ...
},
"_embedded":{
   "custom:sessions":[
      {
        ...
      }
    ],
    ...

Is it possible to do that?