I think any positive relative in a child's life is important.
Do you think they love her?
Do you think they will stick around?
Do they seem like people that are caring?
If you say yes to these questions, then yes.
I have a young friend that was abandoned by her father. She is blind and has CP.. Her mom is a real piece of work, and told her daughter that her father and his family had disowned her.
About 4 years ago, the fathers family found her on FB (she was 21 at this point) and said none of this was true. That yes, her father had turned out to be a drug abuser and total loser, but they had never abandoned her. They had mailed letters, gifts, packages.. and all of them were returned by this girls mother. They still had all of the mailed boxes and letters saved for her. As you can imagine once this girl realized that this other family had loved her and been trying to get in touch with her all of this time, they were overjoyed.
My friend now lives with one of her Aunts. They are all very close. My friend says she wishes she had not missed out on knowing this other family all of this time.
And so if this other family is going to be a good influence and be a stable force in your daughters life, yes, your daughter should be able to see them and have them in her life.