I've always issued bilateral modifications when adding funds incrementally to a contract. I do this because I want the contractor to acknowledge that it can continue working up to the new amount and that it knows that any work performed beyond the funded amount is at its own risk.
I've got someone telling me that this type of modification can be made unilaterally. I can see where this person is correct, but I'd like to know what the proper method is. Should a modification to add funds incremetally to a contract be made unilaterally or bilaterally.... or does it even matter?