RE: What is your suggested process for TUPE transfers inside Talent?
I haven't completed TUPE within Talent myself but I've worked through TUPE scenarios many times and am extremely familiar with the functionality in Talent. My suggestion to you would be not to add the workers to Talent until you have reached the point in the process where liability issues have been resolved and you can confidently state the start date of each transferring employee with the receiving company.
As far as how to import these workers, there are two mechanisms, the data migration framework or using the Excel add-in. I've used both to create worker records and found both to be successful. I use them interchangeably depending on the level of complexity in the client's data.
Hope that helps,
Tom