In-laws keep overriding how we raise our baby, causing tension, how to set boundaries?

This is such a common Malaysian family struggle, three generations under one roof. What helped us: my WIFE (it was her mum) had to be the one to talk to her own mother, not me, that's crucial. In your case your spouse must step up, because boundaries land better coming from the blood relative. We approached it with respect, not confrontation: 'Mak, we really value your help and experience, the doctor advised us to do it this way for baby's safety, can you help us follow it?' Framing it around the doctor/expert takes the ego out of it. Also give her a defined role she owns, so she feels valued. It took months and patience, but acknowledging her while holding firm on key safety things worked. Your spouse aligning with you is non-negotiable though.

I went through this exactly. First, you and your spouse MUST be a united front in private, decide together which things are non-negotiable (safety, feeding, sleep) and which you can let go (small stuff, just relax lah). Pick your battles, don't fight every little thing or you'll exhaust the relationship. For the important ones, let your spouse gently but consistently reinforce it with their own parent. The elders come from love, even when it's frustrating, so acknowledge that first: 'We know you love baby.' What changed things for us was involving her, asking her opinion on non-critical things so she felt respected, which made her more willing to follow our rules on the critical ones. Consider talking to the paediatrician together so everyone hears the same advice from a professional. Patience, but firm on safety.