IDieServices

// Get Cimatron Access
CimAppAccess.AppAccess CimAppAcc = new CimAppAccess.AppAccess();
CimAppAccess.IApplication CimApp = (CimAppAccess.IApplication)CimAppAcc.GetApplication();
// Get Active Assembly Document
var pdm = CimApp.GetPdm();
CimAppAccess.ICimDocument openedDocument = CimApp.GetActiveDoc();
IAssemblyDocument assemblyDocument = openedDocument as IAssemblyDocument;

// Get Assembly Model
var modelContainer = ((IModelContainer)openedDocument);
IAssemblyModel aMainModel = modelContainer.Model as IAssemblyModel;

// Get Die Services
var DServices = assemblyDocument.GetDieServices();
interop.CimDieAPI.IDieServices dieServices = DServices as interop.CimDieAPI.IDieServices;

// Get Force Service and set main assembly Model
interop.CimDieAPI.IDieForceService dieForceService = dieServices.GetDieForceService();
dieForceService.SetMainModel(aMainModel);

/// import clr
import sys

# Add references to required Cimatron interop assemblies
# Adjust paths if needed
clr.AddReference("CimAppAccess")
clr.AddReference("CimDieAPI")

from CimAppAccess import AppAccess, IApplication, ICimDocument, IModelContainer
from CimDieAPI import IDieServices, IDieForceService, IDieForceData

# ------------------------------------------------------------
# Get Cimatron Access
# ------------------------------------------------------------
cim_app_access = AppAccess()
cim_app = cim_app_access.GetApplication()

# ------------------------------------------------------------
# Get Active Assembly Document
# ------------------------------------------------------------
pdm = cim_app.GetPdm()
opened_document = cim_app.GetActiveDoc()

# Cast to AssemblyDocument
assembly_document = opened_document # Python does runtime casting
# ------------------------------------------------------------
# Get Assembly Model
# ------------------------------------------------------------
model_container = opened_document # IModelContainer
main_model = model_container.Model # IAssemblyModel

# ------------------------------------------------------------
# Get Die Services
# ------------------------------------------------------------
die_services = assembly_document.GetDieServices()

# ------------------------------------------------------------
# Get Force Service and set main assembly model
# ------------------------------------------------------------
die_force_service = die_services.GetDieForceService()
die_force_service.SetMainModel(main_model)