Not sure if this would be better in the multiples section, but will try here anyway. Our friends are struggling a little with getting on top of the biting among their triplets. It seems to be mostly two of the triplets but the other (identical) boy in particular biting the third one really quite hard- he's now covered in marks all over his back. They've tried all the techniques they can think of- separation, making a fuss of the bitten child, "naughty step", although they acknowledge that at just 2 and being slightly behind due to prematurity and still non-verbal the naughty step may be of limited use- they mostly use it to separate biter from bitee.
My friends are handling their situation amazingly well (they also have 4yo twins) but are finding this more than a little trying and I wondered if anybody had any advice for them.