My sister is jail now for her DUI arrest

If you hire an attorney, your attorney may file a motion to reduce the bond. However, there is no guarantee that the attorney will be successful but there is more likelihood of reducing the bond with the assistance of an attorney then to try to DIY.

An attorney can file a motion to reduce bond regarding the probation violation or both matters. The attorney will need to litigate that motion successfully. Every judge is different so, once you have retained an attorney, listen to him/her regarding what steps you and your sister (while in custody) can take to make the judge more receptive to such an argument. It has been my experience that judges seriously frown upon new charges while someone is on probation. A new DUI charge while someone is on probation for DUI is something almost any judge is going to take exception to on their docket. I would strongly suggest, once you have retained an attorney, talking to that attorney about coordinating in-patient treatment for your sister to combat her chemical dependency. I have found this to be far and away the best chance someone has for, not necessarily a reduction of bond, but for a furlough to address the issue and prove to the court that the defendant has a legitimate desire to conquer chemical dependency.

Contact an attorney in your area to discuss the particulars of what bail review rights might be available in your area, depending on the particular situation. Depending on your State's rules, the attorney may or may not be able to represent your sister only for the bail review, or could be required to handle the entire case, but they'll know the particulars in your area. Generally speaking, your sister will be in an overall better situation by hiring representation who will be able to explain all of the rights that may be available to her, and the risk/reward of taking any plea or going to trial on the matter.

Be careful what you do here. She is going to serve some mandatory time. Right now she is probably getting double credit for time served (against the VOP and the new charge). Getting the Jail time out of the way is not to be discarded lightly. Tough love, but maybe smart.

It's possible. It'll depend on the judge your sister's case is in front of and the exact nature of her previous charges as well as the new ones. If you want to help your sister, start speaking to attorneys before her next court date. Best of luck to you.