Option to show all images of subgallery together

Hi! I have a gallery that is divided in subgalleries.

Say, the top folder is named "Birds".

Then there are subgalleries like "Blackbird" "Mockingjay" "Eagle"

I would like the gallery on the front page to show all birds.

However, when I activate the option "Show subgalleries" then it shows me the images in the folder "Birds" - logically there are none. Then it shows the word "Subgalleries" where I can toggle through.

I would like to show the images of all subgalleries - is there a way to do just that?

Until I found Droppics I used another gallery, there was a button "show all images of all subfolders" - I need exactly that.

Thank you in advance!