Can you tell me how I can update existing records in a Zoho Creator form using data I have in an Excel sheet? The Excel sheet has a primary key, which I could use to key updates for the Zoho form data, which also contain the same key. 

Here's the functionality I'm hoping to achieve: 

1. If the keys match, I would like to update/overwrite all the fields in the corresponding record using the Excel sheet data.

2. If the keys don't match, I would like it to create a new record and populate it with the fields in the Excel sheet. 

I've tried the desktop migration tool with Excel, but it's not working; I'm having weird problems with selecting an existing form in an application (some of the names listed there aren't listed anywhere in Creator!).

The Creator import functionality doesn't appear to accommodate this, can someone clarify?