I understand that you are saying the calf is now nursing the cow and getting enough to eat. At least that is what I hope you are saying. I think many of us have become invested in this story, and we hope you won't leave us hanging. If the cow and calf are doing well without help, then your sister is right to let them be. I hope you will continue to keep an eye on them while your sister is on vacation. If she starts to go downhill, please don't let her die. Feeding a calf a bottle is not difficult and is really kind of fun. If the cow can't raise the calf it would be better to sell it to someone who has the time and ability to feed it.