How to Assign Specific Pico to Specific Dimmer

I'm experiencing an interesting situation, and need advice on how to proceed.

How do I assign a specific Plug-in Lamp Dimmer (PD-3PCL) to one Pico (PJ2-3BRL) and an Original Smart In-Wall Dimmer (PD-6WCL) to another Pico (PJ2-3BRL)? Right now both Picos operate both dimmers.

I forgot to mention that there is a Smart Hub Pro in our configuration.

If you've not already done so, add both the switched to your caseta system using the Lutron app. Then add the Picos using the Lutron app. One of the settings for the Pico remotes in the Lutron app is what switch(es) they will control.