I would also like to add that many years go, a caretaker at a school I was working at had the tragic experience of having to cope with his son’s death. Unbeknown to him, his eight year old son had been playing on scaffolding on the school building at the time and had fallen onto the playground tarmac.
It resulted in the caretaker deciding to have an operation to reverse his vasectomy so that he and his wife could try for another baby, and they were successful.
I sincerely hope, Liveinnan, that this experience of your daughter and her partner undermining your authority in your own home will lead to a better way of going forward for all of you from now on.