
Explanation:
Box 1: Use a transaction scope
The TransactionScope class establishes an ambient transaction in .NET. (An "ambient transaction" is one that lives in the current thread.) All connections opened within the TransactionScope participate in the transaction. If different databases participate, the transaction is automatically elevated to a distributed transaction.
Box 2: New-AzureRmSqlServerCommunicationLink
New-AzureRmSqlServerCommunicationLink: Use this cmdlet to create a new communication relationship between two logical servers in Azure SQL DB. The relationship is symmetric which means both servers can initiate transactions with the other server.
References:
https://docs.microsoft.com/en-us/azure/sql-database/sql-database-elastic-transactions-overview