T.H.
I'm not aware of one, but honestly it seems like a risky idea. The two types of strollers are different sizes and shapes and it would be hard to get them connected safely I would think. Are you a part of any mothers of multiples groups...maybe someone would have a triple stroller you could buy from them used? I don't know how old your twins are, but my daughter stopped really using a stroller around 2-3, depending upon where we were and what we were doing. Now, if you're by yourself with all 3 of them, then I can understand wanting to strap them all in for sure, wish I had a better suggestion!