Who is Ulrika Jackson from The Settlers and what is their importance?

Ulrika Jackson is Kristina's best friend. Like Kristina, Ulrika is from Sweden. She had been sold into service as a young girl, and she had borne several children out of wedlock, something that earned her a lass than favorable reputation back home. In America, she marries a Baptist minister and has two daughters and a son. She is described as a loyal friend.