Synchronizing/sending data between threads

The app is written in Delphi XE.

I have two classes, a TBoss and TWorker, which are both based of of TThread. The TBoss is a single instance thread, which starts up and then will create about 20 TWorker threads.

When the boss creates a instance of TWorker it assigns it a method to call synchronize on, when the Worker has finished with what it's doing it calls this method which allows the Boss to access a record on the Worker.

However I feel this is a problem, calling synchronize appears to be locking up the whole application - blocking the main (ui) thread. Really it should just be synchronizing that worker to the boss thread....

Previously I used messages/packed records to send content between threads which worked well. However doing it this way is much cleaner and nicer.... just very blocking.

Is there a way to call Syncronize in the worker to only wait for the Boss thread?

My code:

    type 
      TWorker = class(TThread) 
      private 
        fResult : TResultRecord;
        procedure SetOnSendResult(const Value: TNotifyEvent);
        ....
        ....
      public
        property OnSendResult: TNotifyEvent write SetOnSendResult; 
        property Result : TResultRecord read fResult;
        ....
     end;

    ...
    ...
    procedure TWorker.SendBossResults; 
    begin 
      if (Terminated = False) then 
      begin 
        Synchronize(SendResult); 
      end; 
    end; 

    procedure TWorker.SendResult; 
    begin 
      if (Terminated = false) and Assigned(FOnSendResult) then 
      begin 
        FOnSendResult(Self); 
      end; 
    end;

Then in my Boss thread I will do something like this

    var 
      Worker  : TWorker; 
    begin 
      Worker              := TWorker.Create; 
      Worker.OnTerminate  := OnWorkerThreadTerminate; 
      Worker.OnSendResult := ProcessWorkerResults;

So my boss then has a method ca