Grandparents have authority to correct your child?

Just curious of how you all feel or handle your parents/in laws correcting your baby? I just want to start off saying my MIL is a sweet gentle woman and has helped me alot and kept my little guy while I work since Ive been 6 weeks pp. Which has been amazing and helped keep our son from having to be put into daily daycare. Anyways, since then my husband and I have told them we are just saying no no and redirecting him for the time being until hes a little older and can understand a more firmer correction. Well...my father in law is more of the stern (I'll whip if you dont listen the first time) kind of guy. Usually my husband would be too but has agreed with me that our son is still too young for that kind of correction. About a month ago my FIL smacked my sons hand and said he was going to whip him if he got something off the table again 😑 my husband nipped that in the butt and had a talk with him about it. Well tonight my son has discovered the plug ins in our home, and before I could get to him or to correct him on my own, my FIL got to him and smacked his hands.

I do know my son needs correction in life and I need help raising him to be a good person but at the same time how do I get them to let my husband and I do our way for now? Dont get me wrong, my in laws are great people and helped us out in many ways plus they live very close to us. I dont want to cause tension in our family over this but I dont want to have to worry about him trying to whip my child all the time. Sorry for the long rant guys, just looking for helpful advice.