Conversation so far:
where did the cone sisters live in baltimore
The two sisters lived in adjoining apartments on Eutaw Street in the Bolton Hill neighborhood of Baltimore for fifty years.
what were the cone sisters known for
Together they gathered one of the finest collections of modern French art in the United States.
in which state were the cone sisters born
The Cone sisters were born in Jonesboro, Tennessee.
were the cone sisters married
Neither of the Cone sisters were married.

Question: who were the sisters friends with
Self-contained rewrite: who were the cone sisters friends with