I would start by filing with Juvenile Court.  We live in Ohio and my situation is different becuase my son is the one filing for custody due to abuse, but everything has been with Juvenile Court and I've seen other grandparents there with custody of their grandkids working on custody issues.  I would start there and maybe get CFS (Children and Family Services) involved.  If CFS gets involved they can ask the courts to give you custody.  Hope this helps.