Both good names. Neither go with Dorothy
Dorothy Grace works
Dorothea Grace (hmmmm)
Autumn Grace
Grace feels like a good middle name.
Autumn Rose (too twee?)
To carry off dorothy as a middle name needs a stronger first name. I cant think of anything it goes with.
My beloved dgm was Dorothy. I couldn't see my way to using it as middle name
How about
Iris Dorothy
Lena Dorothy
Leia Dorothy
Camilla Dorothy
Hazel Dorothy (nature name)
Charlotte Dorothy (this one i do think is a strong first name)
Eleanor Dorothy (also strong)