Is it correct, that "_wpcf_belongs_artist_id" is a custom field key?
So one approach would be to add this to the query like:
function wpa_filter_home_query( $query ){
if( $query->is_main_query()
&& isset( $_GET['_wpcf_belongs_artist_id'] ) ) {
$meta_query = array(
array(
'key' => '_wpcf_belongs_artist_id',
'value' => array( $_GET['_wpcf_belongs_artist_id'] )
)
);
$query->set( 'meta_query', $meta_query );
}
}
add_action( 'pre_get_posts', 'wpa_filter_home_query' );
Doing this, my aim is still to get the correct post with "index.php?_wpcf_belongs_artist_id=24&artist=sam-sample" (24 is a sample id for the parent page) as a first step. Once this is working I can think about rewrite rules.