My ex-husband died a couple of months ago. This has devastated our child. He had remarried and had another child with one on the way when he suddenly died. Our daughter, 11 years old, has never gotten along with her step mother. The step mother is now refusing my daughter to have any contact with her brother, who she is very close. She has not met her new little sister, but the step mother refuses all contact now. The step mother wrote some horrible, verbally and emotionally abusive words to my 11 year old in an email. As much as I want to never speak to this woman again, my daughter wants to have contact with her little brother and sister. Is there such a thing as visitation for siblings. We don't even live in the same state, but phone or letter contact or something since the father of the children has died.

Its highly unfortunate that his spouse is acting up like this. It could be in part due to the pains of losing someone so quickly and unexpectedly. Time should wear that veil thinner as it goes by. As for the law at this time Im not aware of any state that gives sibling visitation rights in the perspective your talking about i.e. by force. Keep anything she sends as far as emails go and try to keep tabs on her so your daughter can know where her siblings are. It may be possible to reunite them at some point but from the sounds of it right now isn't it.
BTW.. Have you applied for survivior benefits from ssi for your daughter ?