How to choose what face gets Intersected

When I tried to Intersect a donut with a cube, I could not get the donut to be cut into.
I hope the picture helps show what I want.
Intersect test.skp (236.8 KB)

You need to open the donut for editing, then intersect the face with Model.
GIF 16-01-2022 10-04-14 PM

What I don’t understand is why it will intersect the box without opening it, but will not the donut. What rules are applying.

It’s not intersecting the box, the edges showing on the first one are outside the context of each group.
Move the box and the donut and you will see the edges sitting there.

Ok, thanks. I think I understand better now. Missed that point from Aaron’s Square One.

‘Intersect Faces’…
… > ‘With Model’ or
… > ‘With Context’ or
… > 'With Selection´…
will only create new edges in the environment you are currently working in.

In your example:
. when being in top level: just edges outside both groups
. when being in the box group’s editing context: edges that merge with the box’s edges and faces
. when being in the donut group’s editing context: edges that merge with the donut’s edges and faces

He had seen it.

It happens.