The easiest way around this is to install a secondary browser (or use a profile in firefox, but that is cumbersome) for work. They could use a different DNS provider in that browser. I use Brave for this and Firefox for my private stuff.
Or they could ask their employer to pay for a VPN services that comes with DNS. Your family member will then have an easy to understand and easy to spot (VPN is ON) way to 'go into work mode' and out of it for private.