yes this type of situation it is necessary that to use of formula milk. So you can use Aptamil Gold formula milk as use by my cousin. This improve the immunity power.

Breastfeeding is best but if she want to choose fm, choose Prebiotics and HMO rich FM. Because it helps to increase immunity and healthy gut.

Breast milk is the best for the baby. But if you want to go for fm then try Aptamil gold formula milk stage 1. It has HMO and prebiotics which helps in overall development.

Breastmilk is good for baby but if your sIL is not able to feed then go for aptamil gold formula milk.

Consult your doctor with her Yes and try Galact Granules (a ayurvedhic product) which increases breast milk.