Is there any issue with proceeding to go foward with the original requirement plan after the contract modification has had it's requirements de-scoped?
If two each of “Mod X” is still a valid requirement then it is appropriate to again modify the delivery order to install two rather than one now that additional funding is available. From reading your question I assume the requirement hasn’t changed; the decision to install only one versus two was driven by lack of funding and the recognition of the additional risk that would result. Now that funding is available and the desire is to reduce the risk by installing two seems totally appropriate. Obviously all the funding rules will still apply.
Open full Question Details