It would be helpful if we could associate multiple contacts to deals via object ID on an import. If there was a way to put multiple contact object ID’s in a column of the spreadsheet, formatted with a comma or semicolon in between the numbers, this would save a bunch of time.
As this is inbuilt functionality through the UI I was very surprised to find this wasn’t a core part of the import routines. Manually updating thousands of records is going to be a painful and laborious process.