Two exports use slightly different names for a supporter ID. Importing first makes it harder to see which source row caused a duplicate or missing value.
The team can review a field map, trial file and exception list against the destination template before deciding how to handle the records.
A membership export contains two rows with the same member reference and a blank renewal date. A fictitious equivalent shows where the target would need a decision.
The data owner decides which record to keep, what may be transferred and how to handle consent or communication preferences.
One source, one target template, up to 100 de-identified sample rows. The rehearsal does not make a live import or decide how to merge people.
Name the source and destination and describe the fields in general terms. Use fictitious supporter examples.