Yes, lots of things grandparents can do when the parent does not want the child to attend the Kingdom Hall..reading the Bible Story book. Having friends over for a meal, or a get together (especially when there are other children her age), walks in the park talking about Jehovah's creation, singing songs, Sophia and Caleb videos.
And the child can truthfully answer that (s)he did not attend a meeting.
This is the sneaky, conniving, disrespectful mindset of the typical JW. Theocratic warfare indeed!
I would not allow one to walk a dog, let alone spend five minutes unsupervised with a minor.