I'm pretty sure the mod doesn't currently support Vehicle Grid, because that's the only mod I have that affects equipment grids that isn't on the current list, and this mod has had no effect on my equipment grids at all so far.

That would make sense. As far as I am aware, the mod as it stands only affects the very specific grids in the listed mods.
When you say Vehicle grid I assume you mean https://mods.factorio.com/mod/VehicleGrid ?
I can see what I can do about adding it.

Added, tested, and updated the mod. Schall grid categories should now be added to the grids created by the Vehicle Grid mod.
Let me know if it works fine for you or if you want any changes/tweaks.