I have put orphans into my backs as well. But since, I mostly piece tops for Project Linus, I save up all the "extras" of any blocks even the smaller units until I get a pile. I will join "like" extras into strips before I add them to the pile. Black cotton (I like Kona best) is my best friend when I get to work on this pile. I assemble them into strips for either vertical or horizontal placement. I use black strips for the stripping between blocks or strips of blocks. Somehow this works and really turns into some of my most interesting and colorful quilts. Kids love their "covers" and they are the exact opposite of quilt police types. They know someone cares and that's all that matters to them.