:D
try checking out her local la leche league group. they have TONS of info.
or www.askdrsears.com
the most important thing to remember about weaning is that you have to replace nursing with something else to give the child that emotional connection. my son self weaned by 19 months - which was way earlier than i expected, but we replaced that time spent nursing with time spent cuddling or reading books. another GREAT method if shes willing to be more patient with it is dont ask dont refuse. basically, if baby doesnt ask to nurse, dont offer, and if baby does, dont refuse. this is a respectful way to handle a nursing older baby. if she knows baby is going to want to nurse, she can try to distract baby by reading or bath or cuddle or something very one on one with baby. something very connecting without the nursing.
also, dont sit in a familiar nursing spot. around the time my son weaned, we got different furnature from a friend - i dont think you need different furnature, but perhaps just not sitting in the same chair or spot on the couch. it was a given that when i sat on my end of the couch, my son would want to nurse. so avoid, get rid of, or dont sit in the place you usually nurse.
however, if she continues nursing once or twice a day, you can avoid the whole milk thing altogether... kids who are nursing during the 2nd year DONT need whole milk, just skim.
ANOTHER thing, my son wouldnt take to milk either - but he would take chocolate milk. our doctor and wic were both supportive of it - they said as long as he is drinking it didnt matter if it was chocolate or plain. :D that would be a really good way for her to get onto milk. its a really good idea to just get on soy milk - cows milk is being shown now to actually cause more problems than it helps. you DO NOT need milk for calcium or other nutrients as long as baby gets a diet with plenty of veggies, fruits, etc good foods.
im no vegetarian by any means, but reducing the amout of animal products we use is always a good thing.
anyway, good luck to your sister. just remember she needs to do this delicatly, and in a way that somehow fulfills the needs of the baby! nursing after a year however is GOOD, NATURAL, RESPECTFUL, and very very healthy! the longer she nurses, the more various cancer risks lowers, the more diabetes risks lowers, the more weight she will lose (i lost 5-8 more pounds when i continued breastfeeding after a year) and the more antibodies baby will receive! its a good thing
HOWEVER, if mom is unhappy with it, it frustrates her, its a bother, she should stop. again, if you contact the local la leche league they will have LOTS of information for her, and mom support and experience!
good luck!