Both of KneeGuardKids2 and KneeGuardKids3 are not available for car seats with Support Legs.
In the case of KneeGuardKids2, it is possible to use it in infant mode.
However, when the child grows up and it is not available for junior mode, it is not recommended.
If there is a person using the KneeGuardKids with support leg car seat, they may using it with infant mode.
You can use KneeGuardKids if you can remove support leg or fold it to car seat bottom,
It is more important to show the performance of the car seat itself,
Removing or folding the support leg is not recommended.