One more question, as the feature is not here yet.
I am using the following function to display a right sidebar on my child pages :
add_filter( 'generate_block_element_display', function( $display, $element_id ) {
global $post;
if ( 1560 === $element_id && (( is_page() && 932 == $post->post_parent )|| is_page(932) ) ) {
$display = true;
}
return $display;
}, 10, 2 );
It works well, however the CSS related to the block is not always generated…