PTO with ATO Model Underneath ATO Model

Hi

I have the following scenario, I have to Configure the Model with the following Scenario

PTO item or Model

——> ATO model —> Bom Type as Model

—> Option Class —> Phantom

—> Option Choice —→ Assembly Pull or Operation Pull

Again a ATO model —> what should be the Supply type ? Phantom or Assembly Pull, because i use to sell the ATO Model as standalone Model also, How to Handle this situation