We are planning to refresh our DEV Sandbox (Used for Integration Testing) from Prod.

I am trying to identify impacted areas and how I can address those post refresh

One of the identified areas - User Management 

There are many developers who don't have PROD access. They exist only on Sandbox.
Post refresh these users will be deleted. So

1. How can I identify all users who exist on sandbox and not in Prod?
2. Once identified is there a way to automate user creation of identified users not existing on Sandbox? (Post Refresh)

---

Thank you for your reply... I am still evaluating what will be the best approach for us to overcome these challenges...Other challenges I am facing are as below 

* The sandboxes we are targeting to refresh are DEV Sandboxes, hence all the data came through integrations as well as manually seeded data for testing will be wiped out. Data available through integration (for Account and contact) can be brought again but manually seeded data (for other objects) has to be restored using data loader (possibly through CLI)
* Consumer key for connected system also gets updated, hence the integrations will be impacted. The new consumer key for the connected systems has to be declared again on their side. For example we have connected APP for CPQ
* we have SSO implemented , there is an impact on it as well
* SandboxPostCopy interface seems redundant for my use case as data in any case has to be imported using dataloader
* So email anonymisation/invalidation can be handled by modifying CSVs directly

Please let me know if I am thinking on the right lines, any suggestion is more than welcome