Knowledge Graphs (KGs) are increasingly leveraged in Cultural Heritage (CH) domains to enable structured, interoperable representations of artefacts, people, events, and places. The ISO CIDOC CRM, as a core reference ontology, facilitates semantic alignment and interoperability across diverse CH datasets. However, despite the CIDOC CRM, linking independently developed KGs remains a complex challenge. This paper investigates the process of integrating two KGs collecting knowledge about ancient manuscripts: the Mapping Manuscript Migrations (MMM) and the IMAGO knowledge graphs, both of which adopt CIDOC CRM as their underlying schema. Through this case study, we explore methodological and technical hurdles in aligning entities, reconciling modelling decisions, and preserving provenance and semantics during integration. We discuss strategies for identity resolution, semantic approximation, and metadata enrichment, and propose reusable patterns for future KG linking efforts in the CH domain.