How to add a submenu to a previusly created menu page?

I’m building a plugin that creates a new menu page. This plugin has an extension that I’d like to add new submenu to the menu created in the first plugin.

Menu Page (fist plugin):

add_action('admin_menu', 'dadosimob_menu');
function dadosimob_menu(){
    add_menu_page('Dados Gerais', 'Imobiliaria', 10, 'dados-imobiliaria', 'dadosimob_admin');
}

Trying to add the submenu (extension plugin):

add_action('admin_menu', 'bl_menu');
function bl_menu(){
    add_submenu_page('dados-imobiliaria', 'Busca Livre', 'Busca Livre', 10, 'busca-livre', 'bl_admin');
}

This is definitely not working, can someone help me with that?
Thanks