Sarah-
If they're inconsistent feeders, you could go one of 2 ways. One is cold turkey, treat it like a night waking. Since they're waking for the feed and they're obviously hungry, I don't know if that's the best route. The other way is, like I said, reducing the amount in the bottle gradually. I kind of think it's a coin toss what amount you choose as your starting point, whether it's 3 oz or 8 oz. You could also pick an amount in between. Your best bet for the least amount of unhappiness is to start with 8 oz. Cut back to 7 oz for a few nights, then cut back to 6 for a few, etc. If it happens to be a night where one of them takes less than that, oh well. If one of them takes less than that for a couple nights in a row, you might have a new starting point, KWIM?