First, Sorry for the slow reply. I try to avoid replying late when I can, but it's been a crazy few weeks ( well actually crazy few months ).

A collage option is really out of the scope of this project/wallpaper. The way it works now it would be a lot of work to add that, even when compared to just creating a new wallpaper. And for this wallpaper I am almost only doing bug fixes and some maintenance.

Wish I could help as it's a nice idea. But when it comes to time and effort I think it would be better to create something new. Maybe there are other options out there that I am not aware of.