I'm going to be pretty radical in my response: I think that the couple needs to take an indefinite break from their parents. And even if they reconcile after this, if they have children, there need to be very specific rules and perhaps simply no grandparent time without one parent present. Because these are the kind of assholes who would baptize a child without permission/cut their hair against everyone's wishes/decide deadly allergies aren't real/think modern car safety regulations are stupid/sign kids up for activities without checking...the list goes on and on.