Once a case goes to the Grand Jury you lose your right to the preliminary hearing, since its only purpose is to see if there's enough evidence to tell if you should continue to be held for the action of the Grand Jury or not. Once its gone to the Grand Jury,that's it, its over and its never coming back. Sorry.
There are two different ways for a prosecution to formally charge a felony, either through a preliminary hearing or the indictment of a Grand Jury. The method is selected by the prosecution, not the court or the defense.
I am a Delaware lawyer. You have no right to a preliminary hearing in Delaware. Since you were charged with one or more felonies, the case went to the felony screening unit at the Attorney General's office, and they apparently made a decision to take your case right to the grand jury. This can likely be because they decided to add more charges. You will not get a preliminary hearing. You should immediately retain a criminal defense lawyer. I would be pleased to discuss this case with you in more detail, should you so desire.
The above is for informational purposes only and no attorney/client relationship is intended or implied. Such an agreement can only be entered into by the signing of a retention and fee agreement.