The paper analyzes aspects regarding the product development process of a complex product containing sub-assemblies. The sub-assembly is considered as an independent product integrated in a general assembly. The paper proposes new ideas, adding to the state of art in this field. Thus, a proposed scheme of the product development process is applied with new considerations in the case of a complex product containing sub-assemblies. This scheme contains distinct stages for the main developer, aiming with the general coordination and even the development of sub-assemblies, and third-parties, which develop other sub-assemblies (whether manufactured or not by the main developer).