Stacks girls vertically. The higher resolution you make the image, the more they stack! I've found a weight of around 0.5-0.7 for txt2img works well, along with ((stacked, stkd):1.4), tall, extra arms, extra breasts. Then in img2img at a higher resolution, a weight of 0.3 gets good results. This one only makes huge boobies, sorry (maybe :P)!