If you are issuing orders off of an IDIQ contract then no Subcontracting Plan is required. That is because the subcontracting plan, if required, is required at the contract level and not the order level. You can only have one subcontracting plan per contract. See FAR 19.705-2(e). If the CHESS vehicle has subcontracting plans, if would be on the IDIQ contract itself, not the orders.