Oh no!! What a horrible situation you are in. My MIL also told me to put farax in DD's bottle and when I refused she gave me the "it didn't hurt my kids." My SIL and BIL live with them and they gave their DD farex in the bottle very early and used formula because "she didn't have enough milk." When MIL saw me BF she asked where I got all my milk from and I just bamboozled her with as much information as I could to point out how much things have changed since she had kids. It worked for me and I hope that maybe if you are able to share your knowledge, it will work for you. They can choose to ignore the facts but at least that would be an informed decision rather than just going with what they are told. Good luck and good on you for wanting to do something about it.