Definitions
Merger, acquisition, and transformation aren't the same problem
A merger combines two or more companies into one entity and requires ERP integration to unify data, processes, and reporting. An acquisition means one company's systems and data need to be migrated or harmonized into the acquirer's SAP landscape.
Transformation covers broader changes to business or IT architecture, such as an SAP ECC to S/4HANA move. All three demand data harmonization, custom code alignment, and process integration, using SAP DMLT, System Landscape Optimization (SLO), and SAP SLT.