[Plugin: Custom Post Template] How to use for multiple custom post types??

Great plug-in this should be in the core!

Anyhow I am using this along with custom post types, I have edited line 48 in custom-post-templates.php but it will only work for 1 custom post type?

For instance this works for a custom post type called “housekey”:

$this->add_meta_box( 'select_post_template', __( 'Post Template', 'custom-post-templates' ), 'select_post_template', 'housekey', 'side', 'default' );

Adding an additional post type does not work, plus adding this removes it from regular posts.

I have added multiple times , I just do not get it. This does not work

$this->add_meta_box( 'select_post_template', __( 'Post Template', 'custom-post-templates' ), 'select_post_template', 'post', 'housekey', 'side', 'default' );

or any variation seems to break it resulting in server error or just not showing up.

How can I have it show up for ‘post’ plus multiple customs post names?

https://www.ads-software.com/extend/plugins/custom-post-template/