Is it possible for users to be associated with multiple companies?

Flatfile allows you to set user information and company information during your import. These values can be updated with each import based on the information you're pulling from your server. Currently, Portal 2.0 and Portal 3.0 each handle updates slightly differently. 

Portal 2.0

In Portal 2.0, the only required value in setCustomer is the userId. Everything else will update on each upload based on that value. So, if you do two imports, one with a userId of 2 and a companyId of 3 and the second with a userId of 2 and a companyId of 4, the entire user record will be updated based on the most recent import. After the first import you would see an associated companyId of 3, but after the second import both imports would show a companyId of 4. If you have ever passed a companyId in for a user, that companyId will persist for each import until a new one has been passed in. 

Portal 3.0

In Portal 3.0, the first companyId passed in for a user will persist, and will not update based on any new companyIds that are provided. If a unique user must be associated with multiple companies, we recommend passing a combined user/companyId to the userId field to differentiate between each new company they are importing from.