Does the grandchild currently live with the grandparent?
If the grandchild currently lives with the grandparent, then the possibility of gaining custody is greatly increased. The grandparent would bring a Petition for Temporary Custody of Minor Child by Extended Family Member. Both of the parents have to be served with this Petition. If one or both of them are in agreement that the grandparent should assume temporary custody, then they can sign an Acceptance of Service indicating that they accept service of the Petition as though a licensed process server had given it to them. Saves the cost of the process server.
Avoiding a court hearing
The next step would be for the parents to sign an Answer and Waiver indicating that they agree with the Petition and wish for the grandparent to have temporary custody. That is the "Answer" part. The "Waiver" part is that the parent does not wish to have any court hearing on the matter and is content to have the judge issue an Order granting the grandparent temporary custody. Some judges will require a hearing anyway, so that they can "look everyone in the eye" and determine for themselves if this arrangement is in the best interests of the child.
How long is "temporary" custody?
Some Petitions specify a specific length of time for the temporary custody, such as "until the parents are released from incarceration." Most Orders specify that the custody by the grandparent remain in place "until further Order of the Court." That means that someone has to ask the Court to change the custody back over to the parent. The parents and grandparent can agree on the reversal, write up the agreement and submit it to the Court with an Order extinguishing the temporary custody--when the time is right.
Can this be accomplished if one or both parents disagree with the grandparent having temporary custody?
If one or both of the parents do not want the grandparent to have temporary custody of the grandchild, then the grandparent must wait for twenty days after the parent is served with the Petition to see if one or both of the parents file an answer. If no Answer is filed by a parent, then the grandparent can request that a default be entered against that particular parent and set the matter before the court for a default hearing. If an Answer is filed, then a hearing is still the next step IF the parties do not attend mediation. Most courts require parties to attend mediation prior to a final hearing. The final hearing is similar to a trial and requires the same preparation.