Hi @Evgen Kotov ,
Did you want to create an alias for SQL server instance, then you can move the databases from server A to server B, but the application do not affect due to that change? if I misunderstood, please let me know.
You can using old alias name to create an alias for new instance, delete the old alias for old server, then the application can connect to the new instance using old connection string.
refer to this MS document Create or delete a server alias for use by a client.
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