Current design procedures used throughout the aviation industry include the Systems Engineering (SE) approach. Although this method has been in existence for some time, aircraft are continuing to experience ever increasing scheduling and financial overruns. This has led to the development of the Value Driven Design (VDD) methodology. This VDD technique is an enhancement on the more traditional SE method and employs value objective functions to rank design choices. This theory is very much in its infancy and so many issues still need clarification before it can be fully implemented within the industry. One such issue is the idea of subsystem value and subsystem interactions. Currently, these subsystem value functions are similar to an isolated design approach and appear to neglect any and all subsystem interactions, resulting in a process much like that of traditional SE. The work presented in this paper introduces a methodology to assess these existing subsystem interactions providing justification for either including them within the value calculations or neglecting them. This analysis method will ultimately rank subsystems in order from largest to smallest value contribution and determine the importance levels for multiple subsystems interactions. This data will be computed through the use of Value Influence factors and multiple Inclusion Criteria. Further work will be required to fully implement this method and define accurate boundary conditions to ensure reliable, accurate subsystem value calculations can be undertaken and used within the decision making process.