Supply Planning Orchestration - need to populate Subinventory from "Manage Subinventory Items"

We have a requirement for Requisitions created from planning - where we need to default the SubInventory from "Manage Subinventory Item mapping" in Supply Orchestration process.

Is there a place to write groovy scripts to select the Item# on the planned requisition and use that to extract the data from the relevant PVO

(Manage Subinventory Item mapping) and default the value.