Systems Engineering - Conflict Resolution

In the event that a systems engineer must act as an intermediary between two groups that have gone outside their design specifications in order to reduced cost there are many different things that must be considered
In this example the Navigation & Control team  and the Payload delivery team have both gone over their weight allowance in order to use COTS hardware in an attempt to reduce cost and production time. In order to get the project back on track the systems engineer needs to consider several different aspects of the problem:

How much to both systems weigh, and by what percentage did they go over the allotted weight limit?
How close is the production deadline and how much time and money will it likely cost in order to design custom systems for both approaches?
How much of a benefit is COTS hardware?

The first question is important because the system that weighs more will probably have an easier time reducing its weight. For example, if the amount that the Payload team went over was more than the entire weight of the navigation system, then there is no point asking the Nav team to try and make up the slack.
The second aspect is time. If production is far enough out, both teams can be expected to give plans for alternate, lower weight (although higher cost) systems. Obviously this is not always an option, but having both teams attack the problem will often yield better results than insisting that any 1 team fix the problem alone.
The third question is about determining how much of a benefit you are getting out of COTS hardware in the first place. There are many possible benefits including reduced cost, availability of parts, and warranties. All of these things must be weighed against the cost of redesigning large systems of the UAS in order to meet the weight requirements.

During the process of attempting to validate the weight requirements it is important to keep the customer in the loop. They need to know up front about the potential cost overrun that will come with keeping to the original design specifications. At that point, they can make the decision if they would rather have reduced capability or increased cost (Loewen, 2013).

References:
Loewen, H. (2013). Requirements-Based UAV Design Process Explained. MicroPilot.