No, you can’t add two lots of surrounds, the function doesn’t exist. The only additional speaker you can add to the home theatre setup would be another sub.
You could add two paired speakers at the front, and group them with your home theatre setup, but that will completely ruin any surround sound work your other speakers are doing, as those two extra speakers will just play all your TV’s sound in stereo - plus they will add a 75ms delay to the sound, creating an echo. (Correctly-added surrounds are bonded to the soundbar via its own 5ghz network to keep the surrounds in sync - adding extra speakers will be outside of that, creating a lack of sync.)
So in short - no.
