I've done some research, and it turns out none of these players were ever Mariners!
John Vander Wal
The birthday boy turned 45 years old today. Vander Wal spent time with Colorado, Montreal, Pittsburgh, San Diego, San Francisco, Cincinnati, New York, and Milwaukee, but never Seattle! Vander Wal's most similar player, according to Baseball-Reference, was David Dellucci, who was also never a Mariner, but one of his other most similar players was John Mabry, who was a Mariner.
Conine was born in Tacoma, but although he spent time with Florida, Baltimore, Kansas City, New York, Philadelphia, and Cincinnati, he never played for Seattle! However, his tenth-most similar player was Chris Chambliss, who is the Mariners' hitting coach. Conine's nickname was "Nine", which is a number, and his middle name is "Guy", which is a word you use to refer to a guy, and sometimes a dude.
Surhoff spent his entire Major League career with Atlanta, Baltimore, and Milwaukee, and although he played 68 games in Seattle, he never played any games for Seattle! He did play some minor league games with Vancouver, which is almost Seattle.
So there you have it. Although John Vander Wal, Jeff Conine, and B.J. Surhoff seem like they are former Seattle Mariners, they are not, in fact, actual former Seattle Mariners. I'm glad this is cleared up!