When implementing MBSE in complex systems development, it is never about only ONE model or only ONE language. Instead, there is a need to be able to handle different aspects over time, i.e., to separate what it shall become at the end (the future) from what it is for each specific product con-figuration (the present). This is especially evident in large scale projects with complex products having very long life-cycles. Therefore, there is a need for models capturing the long-time perspective i.e., defining the desired future state of a system, together with models representing the current state of design, and models describing in detail how it will be in the near future. In the paper a structured way how to separate those tenses is presented in a context of complex systems development, allowing for representing multiple realisation models for a configuration item. Enablers for achieving this separation over tenses is discussed, where extensive configuration management is one key aspect.