In the end, it won't matter, right? For immediate relatives, overstays, no matter how long, are forgiven. The only risk I can think of is this administration could detain them and put them in detention until their I-485 is adjudicated. But, that risk is also there if they do nothing. So, IMHO, they should file right away, ideally with an attorney experienced in deportation if they can afford it. Or, if they can't afford it, at least have such an attorney identified so they can call right away if they are detained.