I am just calling it "Merge Geometries" because I got the idea while doing some 3D stuff. It can be a good idea to merge geometries for less gpu calls (Or something, off topic!).
So what a feature that acts similar to the Family one.
Objects included inside the family will be merged into single image files.
Either every object or else individual objects assigned to a group.
Alternatively I could just create those sheets in Image editing software beforehand.
But I hope you can see the convinience of something like this.
If it already exists point me to it!
I would have no idea how to make it, and I am pretty sure it can't be managed by a plugin. (Except perhaps merging the objects into a sprite-sheet at runtime.)
While typing this I found a alternative solution. And that would be to use R0J0hounds Canvas Plugin. I don't know if the canvas slows down the game though.
Still, hope you like the idea.