May I just put the other side of the arguement.
I am a Grandmother, who has had custody of her DGD at times through her almost 15 years.
I have always finacially supported her, as in buying her school uniform, shoes, coats, and most of her home clothes, even when she was/is living with her Mother.
She is my DS's DD, who has always paid maintenance, even when at collage. (parents were young teenagers at her birth)
At times, when she is back living with her mother, and her ex partner (Thank God he is now Ex, for Mother daughter and two siblings sake very violent layabout) we have been stopped seeing her.
We have gone months without seeing her.
There was nothing we could do about it.
Seeing her was on the whim of her mother, (although I do feel under duress from the Ex, but still we were stopped)
Not all Grandparents want to see the child just to spite the Parent, not all Grandparents go to court just to be difficult.
Some, and I would say most, go to court because they love and miss their Grandchildren.