There is no current legal basis for a family court judge to prohibit access by the BC's. They have not been charged with any crime and they had a very close relationship with the girls prior to Allison's death and prior to GBC's arrest. It may have been after the Dickie's were given temporary custody when GBC was arrested that the BC's weren't allowed contact with them but as time has moved on and no further arrests made, they have obviously been allowed contact as being in the interests of the girls.
The BCs have them for a weekend every few weeks.