It depends. Your basic IDQ contract should contain the Ordering clause FAR 52.216.-18. The prescription (FAR 16.506(a) for that clause states it is used " in solicitations and contracts when a definite-quantity contract, a requirements contract, or an indefinite-quantity contract is contemplated." The clause it self also says (Para b) " (b) All delivery orders or task orders are subject to the terms and conditions of this contract. In the event of conflict between a delivery order or task order and this contract, the contract shall control."
So you cannot add a clause to the task order that is inconsistent with the basic contract. I would issue the order based on the current contract and refrain from adding any clauses. As a rule, ordering activities should not add clauses to orders without the approval of the original office that awarded the contract. However, if you and the contractor agree to terms that 1) were not inconsistent with the basic contract, and 2) did not violate FAR 12.302 (c), then a SF 30 modification citing "mutual agreement of the parties" (block 13c) could suffice and they would be obligated. Its the contracting officers call, naturally.