I would like to give this suggestion only, because this is a way that many women stopped their breasts from producing milk without pills when they were no longer offered in the hospitals. Which, this is still the case with most hospitals. I had put a belt around my chest for a few days. Not to tight but enough where there is presure on your breasts. If you can do this under your clothes, great but usually I did it at bed time. what this does, it stops the breasts from getting stimulated and then ingorged(filled with milk). Even thou she dosen't produce as much as if she were pregnant, it can still be enough to be annoying and can cause break through leaking, which is, when you can leak through your blouse and even sometimes your bra. Using a belt more or less tells them that they should not produce anymore milk. Usually after a few days, this sensation starts slowing down or can even stop. Your sister does not have to be pregnant to produce milk. I did for several years before I had childen. This actually happens alot with many women. Some women after being aroused, or when they are around the sounds of crying children, their breasts become stimulated and start leaking alittle or alot. Your sister can try doing this for a few days and if this dosen't help and it gets worse than I would definetly tell her to check with her doctor. Sometimes wearing breast pads can help her feel aliitle more comfortable. I will say this is usually nothing to be concerned about but seeing her doctor is best, just to be sure. I do hope this information has helped you. It certainly helped me.