ᐅ Insulating a mezzanine floor ceiling, roof box (eaves box)?

Hello,

Since the intermediate ceiling insulation in our new house is completely outdated and inadequate, we want to properly insulate it.

We have already obtained 120sqm of WLG 32 240mm (9.5 inches) Isofer panels.
Now I noticed that the roof soffit is not separated, as shown in the first picture.
I am wondering what is the best way to insulate this area.

1.) Should I simply lay the insulation wool neatly up to the end of the roof soffit?

2.) Should the roof soffit be separated, maybe with a vertical board above the wall so that the area can then be filled with insulation wool? Like in the second picture, marked with the yellow line?

3.) Or as it is currently done on one side of the roof? Just stuff the area properly? As shown in picture 3?

Or what is the correct way to insulate this area properly?

For your information, the roof is insulated with continuous insulation above the rafters (continuous exterior insulation).

Neither the ceiling nor the roof have a vapor barrier, so we would do it the same way again and install a "cold roof" insulation.
There will be no floor on top of the insulation. It remains open at the top. Only a walkway in the middle will be installed.