A second DWI would be a felony offense in NYS. However, if the breathalyzer result showed .08, precisely at the legal limit, the prosecutor may be willing to eventually reduce the charge to the impaired. A second impaired would be a misdemeanor offense.
If today is her arraignment and she is a jail case, a public defender should be assigned to do her arraignment. In that way, if you cannot retain a lawyer on very short notice to appear for your sister, she'll still come before the judge. When you get to the courtroom, ask a court officer to point out the public defenders and you can ask them the name of the lawyer assigned to handle your sister's arraignment. Let the lawyer know you're there for her and you're the defendant's sister and you can ask about the bail possibilities.
When she comes before the judge the state may or may not agree to her relase. If they ask for bail, her lawyer would be able to argue for her release. Judges like to know a person has ties to the community, which is why it's a good thing for you to let the court know that your sister has family who cares enough to come to court.
I can't tell for sure whether they will release her or not. That's based on her personal and criminal record, the strength of the state's case, the defendant's ties to the community and the possibility of her being a flight risk. Typically, however, on a charge like this, most judges would release her unless she had a warrant history or some other reason which would make the judge believe that if released she wouldn't come back to court.