I have registered for the Alpha Omega seat that is good up to 70lbs & I also registered for the Century Smart Move convertable car seat. I did this b/c they both come with the tether strap included. We just bought a new Toyota Sienna mini van & I don't see what the tether strap will be attached to. A lady on an airplane flight told me she had another mini van & was not able to use her tether straps either. Are tether straps only for sedans or can they be used in vans also?