First, a little background ....
The gent who did this work is licensed ... as a plumber. Yet, the local courts have twice accepted him as an 'expert witness' on electrical matters.
He did this work in his own home, with a permit, and described the inspector as well informed and picky.
Functionally ... the smaller panel on the left is fed from a basement 'sub' ... and in turn feeds both the panel to the right, as well as a detached garage.
Here's an overview:
Bringing in his ground, he solved his lack of a ground buss by just getting a bigger lug, One wire to the source, one to the garage panel, none to the new panel:
In place of a ground wire to the new panel, the inspector accepted the locknut and added 'teks' screw. Do you think they can carry the fault current to trip the 100 amp feed?:
Here's a closer view of the buss connection. Again, note that there is no 'big' wire to the ground buss. Nor is the neutral wire marked white:
Finally, he "supported" the wires to the panels by deliberately braiding them together:
When I commented that it looked as if he had done this job by fishing his materials out of dumpsters .... his reply was "Why, yes, I did! Saved a lot of money too!"