Is Ultima a relative or just a family friend?

I think she was either the mom's mom or the mom's grandmother.

I don't think she was related to the family at all. She was a midwife or at least delivered the children of the family.

When she arrived, the children were afraid as if they were not familiar with her. I would think if she was a grandmother, the mom or dad would've talked about her with the children.

Never do something permanently foolish just because you are temporarily upset!

I just saw the author's stage adaptation of the novel. I feel kind of dumb for not having even known about the book until now. Anyhow, I think it was a great honor for the Marezes to care for this important lady with no family. She delivered four sons to them, which was really meaningful.

Tony gets scolded for calling her Ultima instead of Grande, a term of respect that everyone in town addressed her by. (Then Ultima says of course Tony can call her Ultima.)

And Ultima mentions later on that she chose not to marry and have children.