so Glen lived in same town in California?
Not in the sense I think you mean. They didn't "know each other" , he was born in Texas and moved to LA. It was from the
Wrecking Crew connection when they hit the big time and started using Capitol's studios in early '63. Brian Wilson started calling in more highly skilled session musicians for his increasingly demanding arrangements.(see Wiki's Beach Boys page)
The Wrecking Crew was a loose association of session musicians who were so tight and dependable that they were basically "first call" for any session work in LA in the '60's heydey of the top 40 pop single.
That's why they're found on so many of 'em.
One notorious example is the Byrds' "Mr Tambourine Man". Legend has it that the only Byrd playing an instrument on that is McGuinn on the 12-string.
Quotes from that Wiki link:
"The record producers most often associated with the Wrecking Crew are: Phil Spector, who used the Crew to create his trademark "Wall of Sound"; and Beach Boys member and songwriter Brian Wilson, who used the Crew's talents on many of his mid-1960s productions including the songs "Good Vibrations", "California Girls",
Pet Sounds..."
"Glen Campbell later achieved solo fame as a singer-guitarist in the 1960s and 1970s, and Leon Russell and Mac Rebennack (as Dr. John) both went on to be successful songwriters and had hit singles and albums."
From Wiki's Glen Campbell page:
In 1960, Campbell moved to Los Angeles to become a session musician
In 1962 Campbell signed with Capitol records.
From December 1964 to early March 1965, Campbell was a touring member of the Beach Boys, filling in for Brian Wilson.[9] He also played guitar on the group's Pet Sounds album, among other recordings. On tour, he played bass guitar and sang falsetto harmonies.
I got a suspicion you may be unaware of Brian's tragic and debilitating anxiety issues which were what caused him to "bow out" beginning with the early touring and which was how Glen came to fill in for him. (from the Wiki Beach Boys page)::
"By the end of the year, the stress of road travel, composing, producing and maintaining a high level of creativity became too much for Brian. On December 23, while on a flight from Los Angeles to Houston, he suffered a panic attack only hours after performing with the Beach Boys on the musical variety series Shindig!.[43] In January 1965, he announced his withdrawal from touring to concentrate entirely on songwriting and record production. For the rest of 1964 and into 1965, Glen Campbell served as Wilson's temporary replacement in concert, until his own career success pulled him from the group in April 1965."