can you let me know the name of the book "Mark Cade"
RE: fragmenting the class diagram, I genuinely advocate against this and do so quite strongly. Fragmentation by itself is not the issue, but almost all candidates who do fragment, never provide a joined-up view clearly showing that their multiple class diagram fragments fulfil the business problem laid out in the domain model. Specifically, they lose many marks because association and multiplicity information between entities.
Finally, I believe that the complexity of the assignments in the exam don't require fragmentation.