Whoa, sorry to see your headaches, a very much more complex setup than I’ve dealt with over the years… Work and personal/family links never crossed her, work was on a PC, WinNT, far from any Apple connection, even my DW’s setup was a split, home iMac, work PC… Haven’t seen any AppleTV or iCloud issues myself, other than my ‘office’ TV wants me to update/replace the Xfinity/Comcast box, unrelated to the Mac updates…
Best of luck, in any case, being retired since '02 has simplified things, ridding us of the last PC, better, as it was a magnet for attacks, gone, the HD destroyed…
weco