Sudocream was quite a good choice- might not be great for the kids, but it's not going to do much harm. Agree with Beewyched- there's bound to be something available for cracked nipples for humans, so that would be great. Rotating the kids is another good idea- but be sure that by this she isn't just getting pestered all the time. Ie- one kid goes in, has a sook, goes back for a few more sooks, you take that one out, give her another one, who starts looking for her drink.....Etc etc.
Beth