How should Aang polygamist marriage work if the point is to make airbender we want the wives and kids survive it not like that one family in fire emblem fates so I suggest the following.
Let's look at Aang being in a polygamist marriage practically, political,financial, living condition, wives's killing each other and cooperate with each other so I said that Aang should have wives lieutenants one from each of the three other elements,Water Tribe waterbending master help defeat the fire nation noble family so in charge of Water wives and cooperation, for the earth kingdom toph only child of wealthy and powerful parents earthbender master invented metal bending lived in lie detector helped stop the earth kingdom be burned to assess in charge of earth kingdom wives who is lieing detecting intruders and acquiring money, azula for the fire nation (if stable enough) can do lightning bending princess of the Fire Nation, took down the earth kingdom's best defended city from the inside and probably the fire nation's most terrifying female to mess with(in stable), in charge of fire nation wives probably with ty lee as her lieutenants (and bedmate) scare anyone from messing with the family be the bad cop in negotiationse, punishing the wives and or children when breaking serious family law.