ADD NELSON: Long before their album sold...

ADD NELSON: Long before their album sold 1 million copies and spawned the No. 1 single “Love and Affection,” Matthew and Gunnar Nelson’s songs could be heard in a certain Laguna Beach neighborhood. . . . “I did hear it, piece by piece, while they were writing,” said Harriet Nelson, the grandmother of the twin sons of the late Rick Nelson, who play tonight at the Pacific Amphitheatre (F2). “They’d play it on the front deck on a soft summer evening and sing for me. I love that. I think they’re wonderful.”