would and haveI have two friends who had trouble bfing. The first one developed a horrendous case of mastitis in both breasts. She was incredibly ill and needed sleep desperately. So I stayed with her and treated her mastitis with herbs and poultices while (with her permission) I nursed her baby. This went on for two days until she felt human again and was able to get a hospital grade electric breast pump. It took her baby eight weeks to learn how to nurse from her breasts, but she persevered and eventually it worked.
My other friend also had trouble bfing and when I got to her house to see how she was two days after the birth, her baby was weak and dehydrated because she hadn't been able to get any milk. With her permission, I bfed her baby because I was really worried about her condition, and I knew breastmilk was the only thing that would quickly bring her back to normal. I also did it to help the baby learn that milk really does come out of breasts, and that she could nurse from her mamma! I think wetnursing a baby who is having trouble with her own mamma's nipples is valuable because the baby learns that breasts are for nourishment, and the mamma learns that her baby is not defective and can bf. All that is usually needed is to get rid of the engorgement and soften up mamma's nipples.
I think nursing other's children in certain situations is the only logical compassionate thing to do. Bfing is nourishment. It is not such an intimate act that it can't be shared. No matter what, breast is best.