Below is an extension method to find root Parent Workflow of current activity
/// <summary>
/// Get root Parent Workflow of current activity
/// <param name="activity"></param>
/// <returns></returns>
public static Activity FindRootWorkflow(this Activity activity)
{
List<string> list = new List<string>();
Activity act = activity;
while (act != null)
{
if (act.Parent==null)
{
return act;
}
act = act.Parent;
}
return null;
}