Wix Pro Gallery - Single Thumbnail for Multiple Images?

Hi guys - what I’m trying to achieve is a single thumbnail image that leads to an ‘Expand Mode’ view with multiple images in the gallery that can be arrowed/slid through.

I’m attempting to do this by loading the images into the gallery via Media Manager, then physically constraining the bounding box of the gallery to only the top image (what I’d like to be the hero). This apparently breaks the functionality of the arrowed click-through in Expand Mode, and is ignored when it’s published anyway.

Is there a better way to achieve an ‘Expand Mode’ style user experience based off a single image click? Essentially, I’m looking for a pop-up lightbox style slider gallery triggered by clicking a single image on the page.

Thanks very much for any help you can offer!