Mr Guy said the children often spoke about their father, and would have a relationship with him, although it would not change things dramatically for the rest of the family.
"He's still the father of our grandchildren. I dare say there will be some contact - we won't be looking for too much."
It could make life complicated, but that was something the family were used to.
"It's just another little challenge in life. Anna's in a very difficult position but the children do talk about him."
Macdonald will face his second parole hearing, at Christchurch Men's Prison, on Monday.
Mr Guy said he had not had to mentally prepare for it.
"None of our immediate family will be in Christchurch so we will just have to wait and see really - it's something we knew was going to eventuate ... One of the things is ... You can't worry about something that might not happen otherwise you will stew over it for no reason."
He would not be waiting by the phone for news from the hearing, but was prepared to listen to what Macdonald had to say.
Bryan and Jo Guy revealed in their recent book their concern about a letter Macdonald sent to them detailing how he spent his time in prison. He suggested that when he was released they might get back together and sit down and have a few laughs, which they found inappropriate, so gave the letter to police.
In denying Macdonald parole a year ago, the board said he had "much to do" and would be required to undertake one-on-one counselling with a psychologist. A psychological report described Macdonald as having "narcissistic traits", while a personality test revealed a "marked tendency to portray himself as having socially desirable qualities" and "can be self-involved and over-value his self worth".
