My son is 10 mos old, and my neice is 6 days old. My sister is having the same issues with needing to supplement as i did with my son in the first couple of weeks, and does not like giving the baby formula. I have given her expressed breastmilk and nursed the baby once while she had to return to a doctor for complications. Is this ok for her baby? I know that my milk is made for my babe, but will it be ok for her baby very occasionally? (my niece is doing very well, I'm just wondering if there is any reason they should not use my milk, or i should not cross nurse her baby in the future if i am babysitting, etc. other than the obvious fact that she needs to build up her supply, which i am helping her with) Thanks ladies!