I finally found an Adam's Tandem Trail-a-Bike, $80 on Craigslist! Now, I can ride with both my sons. When my daughter gets a little taller, I am going to hook this up to the tandem and then take all the kids riding! Can't wait to test it out tomorrow. I can tell that it's an older model by the simple fact that the seat post connector doesn't have new connector. Fortunately it fits the one from my single. Now it's time for a little test ride.