Although, Middlebrook name originates in Europe, I do believe Mary Middlebrook was Native. We can not forget what residential schools did to Natives. Especially in the beginning. Natives names were taken away and given European names as part of colonization and assimilation.
My Great grandmother Hazel Schell said her father's Mother was Native.
This is a very good example of intergenerational trauma the government and religion created and the effects still go on today. Everybody is affected and they don't even realize it.
I would further look into where Mary Middlebrook came from. If at all possible at this point in time.