My little girl will be 2 years and two months when my second arrives. She loves to walk but certainly isn't able to walk all the time. I already have an uppababy and a maclaren, so I'd like to get away without purchasing another buggy. We live in central London, don't have a car and walk everywhere. Do you think I can get away with some combination of sling for the little one and then a rumble seat and buggy board on the uppababy?? Or should i just ebay them both and buy a double?? I love the uppababy and am looking forward to using it again.... Thanks!!