Turning your BabyZen Yoyo into a Carseat Carrier, too
Here is a hack using a lightweight, easy to use, TSA approved toddler carseat. The carseat can be easily attached to the back of the stroller via a Luggage Belt or Hooks.
1) To attach the stroller directly on to the seat, you can use the attachment belts provided with the Toddler Carseat, or Toddler Carseat 2, or you can use luggage belts. The luggage belts will provide a snugger tighter fit, and you simply insert it through the forward facing seatbelt loops on the carseat. If you have a black carseat, I recommend getting a set of two luggage belts that are colored so it is easy to add extra security, easy to quickly find the two ends, and you can always find uses for the luggage belt.
Note: Please take into account stability and maximum safe carrying weight of the stroller before you put your child into the carseat. I am comfortable putting my kid in the carseat attached to the Zoe XLC just because it is more secure and has a higher weight limit. I usually try to limit doing so in the Yoyo. To bypass this issue, see Method 2 below.
2) The second way to carry the toddler carseat while still being able to utilize the stroller is using Think King hooks. Make sure you get a pack of two. It is super easy to hand your carseat on and to take it off for security, gate check, or use. It might hit the legs of the stroller pusher while walking, but nothing that impedes use.