dtds are 16mo and sharing is an issue (not as much as I expected but once or twice a day).
dtd1 bites dtd2, I think when she is having a toy stolen or dtd2 gets in her way. It is usually when I'm out of the room or have my back turned. I will hear dtd1 scream out of the blue (a now recognisable scream) and find a bite mark - on her wrist, or see a wet patch on her hair and find a bite mark hidden. Today I found one on her leg but it was when I went to change her nappy as she was wearing tights so I didn't know it had happened. If I see it I tell dtd1 off and she has stopped mid bite when I've caught it in time. No idea how to deal with it.
I showed her her sister's leg and told her no biting and she seemed to look and listen but not sure how much a 16mo gets that far after the event... by this time I'd picked up dd1 from school and shopped in the supermarket for an hour so was a long time after it happened.