Record source and scope
Capture where the preference came from, when it was confirmed, which channel it covers, and whether it applies to a person, account, or case.
Separate preference from permission
A preferred channel does not override identity, privacy, or policy controls. Route requests needing stronger checks to the designated owner.
Review contradictions
Flag contradictory or old records and show the evidence needed to resolve them. Do not silently overwrite a stated choice.