The 71-year-old singer's children Carnie and Wendy, with ex-wife Marilyn Rovell, say their father is avoiding a tour that would mark the 50th anniversary of the band's hit song 'Fun, Fun, Fun' but insist he is healthy and happy.
Carnie told The New York Post newspaper: ''He is 71 and is doing okay. He is laying back a little bit, which is about time. I want him to do that.
''He has been on the road for 15 years, and he has continued to do whatever he wants.
''I like to make him dinner and hang out, but I want him to slow down.''
Meanwhile, the sisters, who also found fame in the band Wilson Phillips with singer Chynna Phillips, are annoyed by comments made by Yardbirds star Jeff Beck, who recently went on tour with their dad and said he was ''a bit of a nightmare'' and questioned his well-being after he endured years of drug and psychological problems beginning in the 1960s.
Jeff said: ''He doesn't speak. He's clearly in need of attention. But that's just my opinion.
''For four days I sat there and didn't even know Brian was in the room. He was so quiet, he never uttered a syllable.''
Carnie was unimpressed by his comments and said: ''Did he have a beer or what before he said it? It is crass and out there. I thought they had a good time on tour.
''When they were on tour I saw my father every single night onstage with Jeff. He had to sit in his chair to watch him, and when he played 'Surf's Up' my dad was in awe.''
We help you decide who to give your money to.
Nature-inspired songs we just can't get enough of.
Artists are coming up with different ways to entertain and help out this year.
Put these British films about music at the top of your watch list.
The Mifo O5 PROs are some of the most durable wireless earbuds on the market and we can't recommend them enough.
These songs were written for times like these.
Live musicians take a financial hit during the worst health crisis of a generation.