In days gone by, before doctors decided they knew more about mothering than women did, breast feeding was, I assume, the only way it was done, although there was such a thing as a wet nurse. More ordinary people had to manage without help like that, however.
The thing was, often, a woman would continue to have babies until her 40s. In my own family history on both side, that happened. There were twice as many children in my fathers family (12 and maybe 13) as there was in my mothers (only five) but the age spread was just about the same. So the point is, it would not have been possible for an older child to nurse. Maybe the two youngest if enough milk was being produced but not an eight or ten year old.
People a hundred years ago would have a horse laugh at things like this today.