Sextuplits are when a mother has 6 babies. Like when you have twins, they're called twins.
All born at once by one mother would be sextuplits. www.youravon.com/cochalek insane!! insane!!
The only way to have sextuplets on the sims 2 is to use the cheat aging off, then make your sims have 6 babies one after the other, none of them will get any older, so when you have the six, and type aging on, it will be as if they were born at the same time.