You want to look into Managed Apple ID's using Apple Business manger. This will allow you to integrate with your current user login's and use the email address for your business. When doing this it will force users who have already setup accounts using their business email to link that account with a private account and the business email account stays in the business. Here is a link to refer to. https://support.apple.com/en-us/HT210737
We are a municipality with around 25 iPhones. The IT environment is a bit of a wreck which we are slowly trying to get back in control of. Managing Apple ID's is an absolute pain and of course if you forget it, you are really hosed even if we are the owners of the account.
Currently, users use their city provided email address as an Apple ID and they set their own passwords. The problem is that when people resign or leave, then we are stuck without an Apple ID. In the past for schools especially, we would just create a generic email account and then tie all devices to that one login. Surely there is a better way such as a MDM or something that would give us a bit more control. Working on a strict budget, but any ideas on how to handle this scenario are much appreciated.