Mass - Import only some fields for candidates

I think this would be a really helpful feature. In fact, i went through a lot of trouble since this feature is not there. We have an external DB where we accumulate candidate info. I imported all the data through 'Import from spreadsheet' and then we began using Zoho, tagging candidates, writing interview comments etc. Now, there were some two additional fields added to our DB and i wanted to import those fields too (we have some 3000+ candidates) and not lose the changes that we had made in Zoho to some of the candidates. There was no way to do this. I had to look at the log and painstakingly isolate those changed candidates and update the rest of the candidates through spreadsheet import and then manually update the changed candidates in Zoho. This could have been far simpler if i could just import an 'Update' w email ID and the two other columns i needed to change in all candidates. Pls. consider making this feature available as i foresee us needing to use this in future.