Merge, de-duplicate, then maintain it so it stays maintained — with the access and deletion obligations built in from the start.
Records from the shop, the mailbox, spreadsheets and the legacy system become one. The work is in the reconciliation, not the import.
Duplicates are merged by traceable rules rather than by feel — and the decision stays reversible.
Enquiries, orders and messages hang off the contact. Whoever picks it up sees the same state as their colleague.
Subject access and deletion requests are a built-in function, not a database search under time pressure.
Briefly describe your case. We will tell you whether this building block covers it — and if not, what does.