I can’t remember too much of the details because I have only seen it once and that was when I was very young, I’m pretty sure it started with the kids going to visit their grandpa but he dies or disappears or something (or maybe he is working against some sort of force trying to take over the world or whatever) so they either go through the woods or they come across basically this purgatory which is similar to the one in Beetlejuice in that it’s like an office and its portrayed in a comedic light (I also remember an elevator) but I think they have to somehow save their Grandpa to get him back. I don’t remember much more, maybe there was a portal???? I don’t know.
Is it “the scream team”
That sounds a little like “A Wrinkle in Time.” The kids are looking for a dad, not a grandpa, and the office part is when the evil force tries to take over Charles.
Is it one of the Halloweentown movies? But a grandma instead of a grandpa.