Barbra Streisand Currently Boycotting Son-In-Law Josh Brolin's Winter Wedding To One-Time Assistant

Barbra Streisand is currently boycotting son-in-law Josh Brolin's planned wedding to his one-time assistant Kathryn Boyd, RadarOnline.com has learned.

"Barbra suspects that Kathryn is a social climber who's using Josh for his money and Tinseltown connections, but Josh thinks Barbra is just being a meddling mother-in-law," a family friend told The National ENQUIRER, noting that Brolin plans on moving "forward with the marriage whether Barbra likes it or not!"

At the heart of the conflict is Streisand's hard feelings about Brolin's 2013 breakup with actress Diane Lane, sources told The ENQUIRER.

The way Streisand sees it, "Josh is basically marrying his hired help when he once had an Academy Award–nominated actress for a wife," an insider told The ENQUIRER.

The Prince Of Tides star, 73, remains "great friends with Diane," initially matchmaking her with Brolin.

"She was very invested in the two of them, so it broke her heart when they split up -- and she blamed Josh for it," a source told The ENQUIRER.

"The Way We Were" singer and her son-in-law are "both stubborn and outspoken," insiders told The ENQUIRER.

"Josh has bumped heads with Barbra repeatedly," the friend said. "She's tried to lecture him and mother him, but geez, he's a 47-year-old man!

"He just tells Kathryn she doesn't need to kiss up to her."