It is very anoying trying to add grids on children frames because all grids even on separated frames appear with no reason. It has been imposible for me implementing grids since the las update. I have tried using groups but still not work.
Layout grids option in Figma (Shift+G) works for all frames in file. You can’t make visible only one grid and hide the others with it.
If you don’t want to see other grids, you need to remove or hide them individually.
It is impossible to turn off a parent grid and still see a child grid. Turning off the visibility on the parent also turns off the visibility of the child – so you can’t turn them off manually. So no way to view just a child grid alone within a layout.
I also agree that being able to view just a child grid would be super helpful to do more complex layouts.