Can I not change the instancing data after the initialisition in a flex actor?

I am trying to create moving stairs with flex particles rolling down. I am using a moving pattern chop to drive the instancing for a box as stairs, but the boxes dont move. It only kinda works if i enable instancing while the sim is running but the only box that is detected for collisions is the original one and if i initialize the solver again the boxes stop moving. Am i missing something or is that just not an avaible function?

thanks alot in advance

I got it. I need to use a feedback top to override the values once the simulation has started.

New Question
If i make my boxes static (infinite mass) the feedback top doesnt work, but if i make them Dynamic the feedbak works but i cant activate Triangle Collision Direction so the particles just fly through the boxes. Is there a way around that?