Hi I need to know that can we switch pre analyzed parts of the same kind of objects and still validate the design on the basis of prior analysis? For example: If I have 4 kind of plane fuselages and 4 kinds of wing sets. I have done analysis on those for stability of structure and flow of air around its surface. Now if I randomly select a fuselage from 4 and a set of wing? Can I use the FEW analysis results from prior analysis to validate if the choice of wings is right or not or if the plane can fly or not with such combination? Or do I need to do the analysis again on whole structure?

You don't say whether the dimensions are the same. If not, then you would certainly have to redo the stability analysis. Even if the basic dimensions are the same but the shapes are different, flow interactions may or may not affect the stability. However, the previously done work would likely give you a head start on analyzing the new combinations(s).