This is the most egregious grammar mistake I have encountered in a children’s book. Why would you use past tense in the first clause of the second sentence? Did the use of “once” trip up all the copyeditors?
I am not a person who flips out at incorrect grammar. But when it’s in a children’s book? One that’s read aloud again and again and again — and then again the next day several times and on and on for weeks? It gets hard to not get upset.
So when I’m reading this to my son, I always change it so that it doesn’t sound ridiculous: “Once Ella’s Dad SAYS she CAN join them, Buddy and his sisters help HER find some yummy plants for her to bring.”
(And yes, I also have to add the object “her” because the sentence needs it, in my opinion.)
Good thing Buddy, Shiny, Tiny, Don and even Ella are loveable. If this book were about anyone else, I might have to disappear it.