>>>I was envisaging this as letting the user to (to get the Company + Department + Surname order) click on the Company column header, which will then sort the grid by Company, then they can Ctrl+Click on the Department header which will set the order of the grid's recordsource to Company + Department and then they can Ctril+Click on the Surname column header and the full sort order will get set to Company + Department + Surname.

Looking at how Thunderbird (and probably few other apps) sorts, it's the last two or three clicked columns, in reverse. If I click the date column, it sorts by date. If I then click the sender column, it sorts on sender+date. IOW, the last clicked is the first in sorting order, then the forelast* and maybe the one before that.

* a word missing in English... could have said "penultimate" but it sounds pompous and doesn't look related to "last" at all.