Join / Replace Existing Data

I’m not sure whether I have misunderstood how this should work, or whether it is not working properly. I am trying to pull information from another database for individual records as required. I have the information set up for the normal situation, but occasionally there is a change. I thought if I had prepopulated a field, and used the code below, that the repopulated field would be left alone, and the empty fields would be populated with the data from the other database. However, at this stage, all the matching fields are being replaced with the new data.

joinonerecord
“DATABASE”,“TaxCategoryDefinition”,
“REPLACEEXISTING”,“NO”,
“CLAIRVOYANCE”,"",
“SOURCEKEY”,“Category”,
“NOMATCH”,"",
“AUTOJOIN”,"",
“KEY”,“Category”,
“MATCHINGFIELDS”,“YES”

The joinonerecord does not have a replaceexisting option, so this option is being ignored. The replaceexisting option does work with the join statement, but not the joinonerecord statement. When used with the join statement the * replaceexisting* option applies to entire records, not to individual fields within a record. There is no way to have join or joinonerecord operations populate individual fields depending on whether they are currentlly empty or not.

Thankyou. That clears that up. I’ll just reverse the order of what I’m doing!