If you want the best possible integration, you should not run the Maggies full range. An active crossover with a steep crossover rate(24db/octave at least) at about 50-60Hz should be used on both the full range speakers and the sub woofer. If you have two sub woofers, you can place them symmetrically placed on each side of the room, the same distance from each sub woofer, and achieve better integration, and raise the crossover frequency to about 80Hz. A delay should be set electronically to adjust the acoustic phase alignment at the crossover point of the sub woofer and main speakers as closely as possible. If you are using separate preamplifier and amplifier components as opposed to a receiver, it will be easy to add the appropriate device. If you have a receiver, things are less certain. Some receivers have sufficient built in active crossovers, and some do not. Some receivers even have loop jacks in the back where you can add in external devices between the preamplifier and amplifier stages. Most do not have such a feature.
-Chris