Most people can exclusively chestfeed their babies if they have enough help. Use your local
La Leche League for support. Sometimes there is a problem that is difficult to overcome.
Supplementation with formula is the first idea that most parents explore, but you could
supplement with another parent’s chest milk.
https://www.medela.us/breastfeeding/articles/how-to-safely-donate-receive-donated-breast-milk
https://www.llli.org/breastfeeding-info/milk-donation/
https://www.hmbana.org/