where demand for dependent item coming from to calculate safety stock if we don't use forecast

Hi experts,

We have constrained supply planning and don't use any forecasting (Demand management module) for both component and end items.

We will use safety stock for component item only, not for end item since the business are make to order, always manufacturing different item code based on the sales order. So the demand are coming from sales order. But how can we restock the safety stock for component item ? when there are no forecast for end item. For the safety stock calculation we will use days of cover and demand period for components items only.