Alternate keys is the way to go.
You might need to wait for a bit after creating the key for it start working properly.
When an alternate key is created it will initiate a system job to create indexes on the database tables to enforce unique constraints on the columns used by the alternate key. The alternate key will not be in effect until these indexes are created. Creating these indexes may take some time depending on the amount of data in the system.
Check more info on how to track the status index creation (Microsoft Docs site)
Also check this video for step by step demo and details on alternate keys
To find system jobs
- Open you app
- Launch Advanced Find
- Pick
System Jobs
table in Look for dropdown
- Select System Job Type column Equals operator and
EntityKey Index Creation
job type
- Click [Results] button