The alienator, the male parent, is consistently referred to as either "male parent". He's not my "dad". Never was. Never will be. I've never had a "dad" because no real dad would do what he did. I did not live with this person. My sister and I talked to him on the phone once a week at least and saw him every third weekend, usually.
The other parent, the one to whom the campaign of alienation was targeted, my mother, is "target parent" or "mother" or even "mum". I lived with this parent.