I do not recommend connecting your 4 ohm speaker, though I guess they are not power hungry and that the satellites are not driven continuously.
I think I will have to take back my advice. Yesterday I connected a pair of power hungry 4 ohm, 88db Polk speakers with 3 drivers 'each' to the fronts and operated for nearly 3.5 hrs non-stop. Music videos (which would need continuous driving of the speakers) were played on moderate and above volumes. Though the unit became slightly warmer (very mild) than normal, it was absolutely fine. Its clear that impedance is not flat at any fixed value, rather a curve which mostly lies above the nominal rated impedance. A 4 ohm speaker has resistance of 8 ohm or more for majority of the frequency range. It seems that 4 ohm speakers in reality does not draw more than 10-15% additional current of a 8 ohm speaker.