I would too however if there is any truth to some things in Susan's diary about her family that might be the reason why they cannot see the kids.I'd be filing court papers to get those kids the (blank) out of the Powell home.
I really don't know of any court that would deny any grandparent access to their grand child except in the case if those grandparents has a history of abuse of some kind.
I don't know if this is the case...maybe it is just the police asked the family to have less contact to bide their time because one day they will have full custody of them once JP and his dad are arrested.