I have solved the main query:
For WordPress dashboard, I needed the list of all posts related to all post types in:
edit.php?post_type=product
Using the concept of:
edit.php?post_type=product&showall=true
With function in backend function.php
function show_all_posttypes( $query ) {
if( ! is_admin() ) {
return;
}
if( isset( $_GET, $_GET['showall'] ) && true == $_GET['showall'] ) {
$query->set( 'post_type', array('product', 'second_type_product', 'third_type_product') );
}
}
add_filter( 'pre_get_posts', 'show_all_posttypes' );
And after that my all posts related to three post types: product, second_type_product, third_type_product is listing very well on URL:
edit.php?post_type=product&showall=true
But when I am using its feature to filter on edit.php page with all listed posts then is saying:
Invalid post type
I want to achieve every feature support with my list related to multiple post types list on url based on one post type.
Thanks for support!