In an interview with Newstalk ZB's Simon Barnett and Phil Gifford, Carter's dad Neville said although he gave his blessing for his son's move to the Blues, he will still be supporting the Crusaders when the two sides meet.
"It's pretty straightforward," Neville said. "The Crusaders are always going to get the support from me. And I'll just keep my fingers crossed he's not going to get smashed by them."
Dan Carter has long been a loyalist to the red and black, but he says he signed with the Blues ahead of Super Rugby Aotearoa next week because he wanted to "give back" to New Zealand rugby.
However, he still had to clear it with his family down south.
"I talked to the old man," Carter said in his first media appearance as a Blues player yesterday. "He's a proud Cantab, but like he has been throughout my career, he was really supportive. That goes a long way, having that family support."
Neville recalled the conversation he had with his son before he went on to shock the country by signing with the Auckland franchise.
"I said to him 'you've still got a wee bit to give back to New Zealand rugby and we're lacking rugby at the moment. So if you're keen to give it a go, go for it'. There's nowhere else he can go at this stage unfortunately so it's an opportunity to give back to rugby in New Zealand.
"I did say to him 'you may be getting a bit of a bad reception when you get down our way'."
This time, however, nana was happy for her grandson and supported the move – although, like her son, she probably won't be rooting for Carter's Blues against the Crusaders.
"Her father played for Canterbury and her uncle played for Canterbury and the All Blacks," Neville said. "So she was definitely Cantabrian through and through.
"I managed to give her a ring just to actually break the news to her before I thought she'd see it on telly but she said no she's seen it and she's finally decided being the age of 90 that it's quite good he's actually getting back into doing something with his rugby. So she was quite pleased as a whole."
While the days of his son playing in red are long gone, Neville says there's one thing he definitely doesn't miss about that time: those massive underwear billboards.
"We took one look at it and took a u-turn and went back the other way."
- NZ Herald & RNZ