One of our customer has an Import Object on Opportunity.
In the past we used a Single Value Field and it worked fine, but we changed it to Contact SSN, an OOTB, MVF field.
It looks like something does happen, as we do get warning for SSNs that do not exists, but the value doesn't load to S_Opty_Con or any other field.
I have searched, and queried the DB, and learned that there are only 2 cases of using a Multi Valued Field -
in LS Medical Code & Service Locator.
I couldn't find any documantation regarding it, only something on google.
Is it suppose to work? Can we use a MVF in order to import? If so, how can we detemine which is primary?