What are your thoughts on family providing day care? (Such as inlaws)

My mother in law just quit her job to provide day care for my newborn son. I had never asked her to do this and had him signed up for daycare already. She said she would do it for half the price. Hubby doesn't see an issue with it. I dont want her watching him because if something were to happen or if she did something I didnt agree with I wouldn't want a negative issue between us when I dont want her watching him anymore. If a daycare did something I could easily leave the daycare. Thoughts? I thought maybe letting her watch him one day a week.