//Update a person methodvar client = new BFSServiceReference.bfsapiSoapClient();
var credentials = new BFSServiceReference.Credentials()
{
    UserName = bfsusername, //Username of administrative user in your instance of BFS
    Password = bfspassword, //Password of the administrative user in your instance of BFS
};
var response = client.UpdatePersons(new BFSServiceReference.UpdatePersonsRequest()
{
    Credentials = credentials,
    identify = bfsidentifier, //Identifier is a unique token for your instance of BFS
    Fields = new UpdatePersonFields()
    {
      IsApproved  = true,     
    },
    Entities = new []
    {
      new UpdateAccount()
      {
          BrickId = bnpersonid,
          IsApproved  = true,        
      },
    },
     
});
foreach (var c in response.Entities)
{
    Console.WriteLine(c.BrickId + "," + c.IsApproved + "," + response.Message);
}