I may not be able to help you myself, and if you are based in the US then maybe the links and email address can't give you all the assistance you need concerning legal matters either, but they will understand your situation very well I know.
Here is the website link:-
http://www.grandparentsapart.co.uk/
If you write directly to:
jimmy@grandparentsapart.fsnet.com
You will certainly find support as I've said, although they are a group established to help grandparents struggling to get contact with their grandchildren, they have many members who have had to step into the breach when parents fail, as you appear to have done.
I wish you very good luck, and I hope these immature sounding parents get their act together soon for everyone's sake too.
Very best regards and wishes, Graham