New Post: How to add Tracks to already started FilteredStream ?

I added some tracks to a filtered stream and started it as:

filteredStream.StartStreamMatchingAllConditions();

Now when the stream is listening to twitter feed, how can I add more tracks to it to be filtered?

So far I am trying to do something like this:

filteredStream.AddTrack("#newtag");
filteredStream.StopStream();
filteredStream.ResumeStream();

But on ResumeStream() it errors as follows:

The operation is not valid due to current state of the object.

OR is there an alternate of doing this, for example: can I start a stream without any tracks, and when a tweet is received, I would filter its text manually ?