But I paid for my seat and if I did pay to sit next to my wife (which isn’t really a big deal for either of us), I would be really pissed if my seat was changed because a parent was too cheap to pay to have an assigned seat.
My wife and I have chosen a different flight because the seats we wanted wasn’t available.
Of course all of these opinions of mine go out of the window if it truly is an emergency. But even then, at least with Delta, they only allocate a certain number of seats as “basic economy” and once those are sold out - like they might be on a last minute flight - you have to pay a fare where you choose your seat.