Insert birth date only if no birth date on file
Sometimes we have full birthdays on file (mm/dd/yyyy) but our incoming data includes people's incomplete birthdays (mm/yyyy). We don't want to overwrite the complete data with the less complete data. But the "Ignore birthday if not identical to existing birthday" rule currently considers NULL birthdays as an "existing value." So when we use that setting, NO birthdays get imported, because the incoming birthday does not exactly match the existing blank birthday field. But setting the rule to "Update..." means existing data will get overwritten. It would help to have a rule option allowing an update only if there's no birthday on file, similar to the option for address/etc. updates, or to make that "Ignore" rule apply only to actually-populated existing values.
We have a similar situation where if a value exists on an attribute in our donor record, we do not want to apply the value in the field of the incoming record. We now have an orchestration that will only update after querying and evaluating the constituent attribute. Perhaps this is a potential solution for you? Happy to share more details if valuable.