Dionne,
What about a litaf buggy board. Its two tier so Dior can sit on it and have her feet on the step. Im not sure it would fit on the quinny though. Also, I got a double side by side stroller of ebay, new, for £109 inc postage. Its basic but quite funky and is a 3 wheeler style and compact. I cant get into ebay just now or I would post the link.