On-Boarding External Customers - Best way to create ESS Users

Hi Experts,

My company is looking to start on-boarding external companies into our Service Manager, they would idealy like for everyone in the external company to be able to access our Employee Self-Service Portal and submit requests that way.

Now my issue is figuring out the best way to have all these companies users and contacts created.

I cannot use federated services - would anyone have any suggestions as to what they do in these scenarios?

We are currently throwing around the idea of having a Generic Operator per company, and then making a couple generic contacts agreed upon with the company, for them to choose from when submitting a support request. This seems like it probably won't work out very well.