Keep the relationship connected across teams
Start with the organisation, its contacts and the responsibilities on both sides. Add the commercial and service records that explain the relationship: opportunities, proposals, agreed work, invoices and support requests. A useful record tells someone what has happened, what was promised and what needs attention next. Keep the information current through ordinary work rather than treating database maintenance as a separate annual exercise.
Give each team the context it needs
Shared information does not mean unrestricted visibility. Sales, finance, delivery and service have different responsibilities, and their views should reflect that. Decide which documents and updates belong in the customer portal and which remain internal. Agree who resolves duplicates, changes account ownership and reviews stale information. The result is a more dependable handover, especially when someone is absent or the relationship grows beyond its original contact.