How do you let you mum-in-law know that you will be calling the shots on the upbringing of your child (without sounding rude)?

I will tell my MIL my basic list of expectations, e.g. type of food for feeding (never offer sweets or ice cream without my permission), the ways handle children misbehaviors (no scolding of stupid, naughty, etc), and I will prepare some toys and books for my MIL to bond with kids when I am not around. These are the basic things that I wish her to meet my expectations and i will communicate to her nicely and explain the reasons behind. Other things i will just let my MIL choose to do in her own ways as long as put the child's safety first. I would say communication and understanding between both of you are very important to maintain a healthy and happy family and reduce uneccessary conflicts.