Parenting with two different parenting styles.

Sometimes I feel so anxious and frustrated with who I chose to become a parent with. My partner and his mother have been trying to push NIDO on me to help our 1yo. She had her checkup today and is completely healthy and is growing at a steady rate. I asked her about NIDO and she said it’s unnecessary for her and that she’d get the same benefits from cow’s milk. I relayed this info to my partner and he’s fighting me so hard on it. Truly I don’t know if this is his own opinion or his mother’s. He never said anything or brought up NIDO until his mother did. Now I understand he’s a parent too and has opinions but if she doesn’t need it then there is no point to be giving her milk substitute instead of cows milk. It’s so frustrating because we seem to bump heads on almost everything when it comes to our parenting styles. I’m scared that if it continues like this, we won’t make it. I’ve gone back to work part time and honestly I’m scared to leave our daughter with him and my mil bc I KNOW they’d go against my wishes.