I don't even want to guess the percentage of couples where one partner pays for (both, maybe three) phones/landlines, and that's ignoring all children, underage or not.
I don’t bother to update the names on their lines, so they all probably link back to me.
Family plans are pretty common here, so I wouldn’t expect too much friction.
I would absolutely cooperate (obviously through a lawyer) with records if someone else on my family plan did something illegal.
I also have records showing that they pay me for the line.
Also yes, it would be a huge hassle. The probability of that happening is small, and I’m willing to risk it like many other things in life. I only do this for very trusted people.