@booma Welcome to Connect. You are absolutely correct that both your brother and his wife will need a caregiver after surgery. This will be one of the things discussed as your sister goes through the testing to be a donor.
-Here is information from the Mayo Clinic Living Donor Toolkit
Living Donors
https://connect.mayoclinic.org/blog/transplant/tab/resource-36/
Some recipients/donors have chosen to stay at the Gift of Life Transplant House in Rochester. Is that the facility that you are referring to? It is where my husband and I stayed during liver and Kidney transplant in 2009. We were actually there for an extended period before my transplant, too, while undergoing treatment. During that period I saw many recipients and donors coming and going. I feel certain that your situation is not a unique one. Here is the phone number (507) 288-7470 for the Gift of Life House (GOL). If you call during normal business hours, I know that Mary Wilder or one of the staff will be able to assist you and answer your questions.
-website for the Gift of Life House https://gift-of-life.org