Order & OrderProduct Workflow

Based on the status of the order. I want to check the Orderproduct/lineitem and then create a new record for XYZ entity based on the lineitem/orderproduct.

So I started of by
WF1 [order]- creating a workflow on order [to check for order status] and then call the child WF on Order Product
WF2[OrderProduct]- child workflow on Order product which check condition and creates the record for entity XYZ.

Turns out I cannot call/trigger the child workflow based on the OrderProduct Entity.

Any ideas/suggestion for this problem.

Thanks