Question about Thule Chariot Cab 2

We have mounted both at the same time. Works perfectly: the seat support on the left and the hammock on the right.

I'm sure they both work well together. But we only have the Infant Sling baby seat.

I had not installed either of the two seat aids. As soon as the little ones can sit themselves, you don't need to spend extra money on them. Before that, I wouldn't let the children ride in the trailer anyway. It's like so often with baby products. You don't really need the extra parts, they are just an additional source of income for the manufacturer.