Your understanding of interrelationships among functional, structural and behavioral models is something I can agree with. To have an integrated and coherent system, it is essential that each model aligns with the others. The functional and behavioral models use activity diagrams and use-case diagrams/descriptions, while the structural and behavioral models use the same use-case diagrams/descriptions but must align with CRC cards and class diagrams. Similarly, the functional and structural models also use activity diagrams and use-case descriptions/diagrams, but they must also align with the CRC cards and class diagrams. This is not an easy process. However, it can help to establish a strong foundation for your system by testing the interrelationships.