How to set a dataconnection of a DataSet

After some struggling:

public async Task PatchSqlDatasourceCredentials(Guid groupId, string datasetId, string reportingSqlServer, string reportingSqldatabase, string userName, string password)
{
    var pbiClient = await GetPowerBIClient() ?? throw new PowerBiException(PowerBiClientIsNull);

    var datasources = (await pbiClient.Datasets.GetDatasourcesInGroupAsync(groupId, datasetId)).Value;

    var sqlDataSource = datasources.FirstOrDefault(d => d.DatasourceType.Equals("Sql", StringComparison.OrdinalIgnoreCase)) ?? throw new PowerBiException(PowerBiClientIsNull);

    var selectedServer = sqlDataSource.ConnectionDetails.Server;
    var selectedDatabase = sqlDataSource.ConnectionDetails.Database;

    if (!selectedServer.Equals(reportingSqlServer, StringComparison.OrdinalIgnoreCase) ||
        !selectedDatabase.Equals(reportingSqldatabase, StringComparison.OrdinalIgnoreCase))
    {
        await pbiClient.Datasets.UpdateDatasourcesInGroupAsync(groupId, datasetId, new UpdateDatasourcesRequest(new UpdateDatasourceConnectionRequest
        {
            DatasourceSelector = new Datasource
            {
                DatasourceType = "Sql",
                ConnectionDetails = new DatasourceConnectionDetails()
                {
                    Server = selectedServer,
                    Database = selectedDatabase
                }
            },
            ConnectionDetails = new DatasourceConnectionDetails()
            {
                Server = reportingSqlServer,
                Database = reportingSqldatabase
            },

        }));
    }

    datasources = (await pbiClient.Datasets.GetDatasourcesInGroupAsync(groupId, datasetId)).Value;
    sqlDataSource = datasources.FirstOrDefault(d => d.DatasourceType.Equals("Sql", StringComparison.OrdinalIgnoreCase)) ?? throw new PowerBiException(PowerBiClientIsNull);

    var datasourceId = sqlDataSource.DatasourceId!.Value;
    var gatewayId = sqlDataSource.GatewayId!.Value;

    // Create UpdateDatasourceRequest to update Azure SQL datasource credentials
    var updateDatasourceRequest = new UpdateDatasourceRequest
    {
        CredentialDetails = new CredentialDetails(
            new BasicCredentials(userName, password),
            PrivacyLevel.None,
            EncryptedConnection.NotEncrypted)
    };

    // Execute Patch command to update Azure SQL datasource credentials
    await pbiClient.Gateways.UpdateDatasourceAsync(gatewayId, datasourceId, updateDatasourceRequest);
}

Apperently I must  "Replace"  the SQL connection. 
Question: Is it also possible to add or create a connection.

Can I also make the connection based on a Mangedd Identity