Gallery Grid displayed in home box

Hello Site 5,

Another Great Theme. Keep it on, I am working with only your themes for months now !

Just a question I can’t Figure out on my own about displaying a gallery Grid in one box on homepage.

If I use a Gallery Format for my post, it will display as a slideshow, wich is great too. But I would like also to display some of my posts as the Gallery Grid as shown on your Demo.  How to do that ?

If I do a regular post displaying thumbnails, the gallery grid does not show on the homepage box for this post. So how to display this Gallery Grid on the homepage box excerpt (as per your demo)  ?

Thanks in advance for you kind help