Name the systems and the business event
Start with what should happen: a product changes, an order is accepted or a payment is recorded. Identify the source and destination systems and the specific record types involved. Avoid treating “sync everything” as a complete requirement.
Choose the owner of each record
Agree which system is authoritative for each record and field. Define how an existing record is matched, how new records are created and what should happen when values conflict. Include updates and cancellations, not only the first successful creation.
Decide how exceptions will be handled
Describe what should happen when a required value is missing, a record cannot be matched or one system is unavailable. Agree who reviews failures and how a retry avoids creating duplicates. The behavior should be clear before the integration goes live.
Plan access and representative testing
Arrange access through an agreed secure process. Identify test environments where available and use representative, appropriately protected data. Include normal transactions, updates and expected failure cases, with owners from both systems involved in the review.
Define the handoff
Record the mappings, schedule, dependencies and support contacts. Agree who maintains credentials and monitors failures. When a connected system changes, the team should know where to look and who is responsible for the next step.