Adapted from Robert Kimmel Smith’s book, and directed by Tim Hill (an animation veteran, including “The SpongeBob Movie: Sponge on the Run”), the film quickly turns into a domestic war, with sixth-grade Peter (Oakes Fegley of “The Goldfinch”) warning grandpa Ed to relocate, or face the consequences. Unlike his mom, Ed’s daughter (Uma Thurman, an unlikely if effective choice), the kid appears little concerned that gramps is still missing his late wife and struggling on his own with things like, well, driving.The “war” unfolds with a series of escalating pranks, at least two of which leave Ed without his pants, which about sums up the level of comedic aspirations. Fortunately, he has reinforcements (basically seconds in the duel, to counter Peter’s chums) played by Christopher Walken and Cheech Marin, with Jane Seymour subsequently joining in as a welcome new addition to their ranks.As for the generation caught between them, Peter’s folks (with Rob Riggle as his dad) are a slight cut above the usual Charlie Brown-parents in these kind of movies, occasionally getting unwittingly drawn into the conflict. Peter is also a middle child, bookended by sisters with concerns of their own.Edgy it’s not, but everyone seems to be having a pretty good time, perhaps especially the senior class. File it under De Niro’s commitment to be constantly working — augmenting dramatic roles like “The Irishman” with lighter fare, such as the “Meet the Parents” movies and “The Intern” — without excessive fretting about the quality of the material, which he elevates as best he can.The shame of it is that “The War With Grandpa” would have been one of those disposable live-action movies families could have seen together, violating the “Seinfeld” “No hugging. No learning” rule in an inoffensive way. As is, while the film is indeed opening in theaters, under current conditions it’s hard to imagine many people wanting to venture out for a confection that’s basically a TV movie, just with an unexpectedly starry cast.Whenever and wherever kids do see it, they’re apt to enjoy it, while the theme reminds the adults in their lives that the differences and that come between families — from politics to something as frivolous as a kid’s bedroom — finally aren’t as significant as the deeper bonds that they share.In that sense, “The War With Grandpa” might be a slim construct, but at least it carries the message that blood is thicker than water — or, in Peter’s case, real estate.”The War With Grandpa” premieres in theaters on Oct. 9. It’s rated PG.