Although you may have two systems containing customer data, the details in them may have contextual differences. For example, in Dynamics 365 Finance & Operations, you can only have one primary phone number, which is inclusive of landline and mobile phone numbers. Whereas in other systems you can have a primary home and a primary mobile phone number.
Similarly, when it comes to addresses. Although Finance & Operations allows multiple business purposes to be defined on the address (invoice, delivery, etc) only one address can be marked as the primary address. However, in other systems you may be able to define a primary invoice and a primary delivery address.
Top tip: We suggest that you leverage modelling to create visual representations of the data models in both legacy and Finance & Operations. This could be an entity relationship diagram, for example. The diagram will highlight the entities, primary and foreign keys and other constraints between the entities. From here you can visually connect the key data and identify the sequencing.
Also, it’s highly important to get early exposure to the application with real business data. You can simply take a sample of existing legacy data and attempt to manually enter all details within Finance & Operations.