That's not overprotective, at least in my understanding. Overprotective means that you are putting pillows around your child's body so that when she falls, she won't hurt herself, and of course you would monitor her every step along the way so you could catch her mid fall. Overprotective means you would feed her only liquid food in tiny doses so that she doesn't choke. And of course you would never ever let her go out on a date without a 24/7 gps tracker so that you know at every point in time where she is. This is what being an overprotective parent means.

First, your family is trying to help you. That kind of help in the first few months is super important because you (as parents) will get exhausted and deprived of sleep. So try to keep the good relationship within the family.

Second, if you as a parent do not agree with the suggestions on how to raise your child, simply ignore them. Make your own mistakes. It's your child, not theirs. You will likely hear a lot of "I told you so" as the years pass by, but still it's your child and you raise them however you feel is right.

Later in life it will be harder, especially when you leave your child with your relatives for longer periods of time. This is when they will do everything differently. Just have a serious but friendly talk with them explaining why you think it's wrong, why you're doing it differently, and assume they will still not listen to you and do the way they raised you. That's just the way it is :-)

In the end, it's always best to explain to your child why they shouldn't do something even if their grandparents insist on doing otherwise.

You'll get used to that