code.cs

dynamic joData = null;

private void Form1_Load(object sender, EventArgs e)
{
    joData = JsonConvert.DeserializeObject(File.ReadAllText("data.json"));

    ribbonReportingTab1.DataSourceManager.LoadJson(joData.ToString());
    ribbonReportingTab1.DataSourceManager.PossibleMergeFieldColumnsChanged += 
        DataSourceManager_PossibleMergeFieldColumnsChanged;

    MaskDataColumnNames(joData);
}

private void DataSourceManager_PossibleMergeFieldColumnsChanged(object sender, EventArgs e)
{
    MaskDataColumnNames(joData);
}