Introducing a lady to her friend, Juliet said, "Her father-in-law's father's....." How is the woman related to Juliet?

Question

Introducing a lady to her friend, Juliet said, "Her father-in-law's father's only son's, only daughter's brother, is grandfather to my daughter." How is the woman related to Juliet?
Note: My daughter's father's grandfather had only one son and one daughter.

Answer 1

Mother in law

Answer 2

Mother or Mother-in law

Answer 3

She is Juliet's Mother-in-law

Answer 4

sister-in-law